Remove selfbot support

While selfbots have always been "roughly tolerated", lately they have
been tolerated to less of a degree.

The simple answer is to no longer support selfbots in any form. This is
done for a few of reasons: 1) in anticipation of selfbots no longer
being tolerated; 2) there are few reasons why one should make a selfbot
in Rust and not a scripting language; 3) there are alternatives
(i.e. discord-rs) that still support userbots. Selfbots are simply not
a goal of the maintainer of serenity.

Upgrade path:

Don't use selfbots with serenity. Use discord-rs instead.

The following has been removed:

Enums:

- `RelationshipType`

Structs:

- `FriendSourceFlags`
- `ReadState`
- `Relationship`
- `SearchResult`
- `SuggestionReason`
- `Tutorial`
- `UserConnection`
- `UserGuildSettings`
- `UserSettings`

Removed the following fields:

- `CurrentUser::mobile`
- Ready::{
     analytics_token,
     experiments,
     friend_suggestion_count,
     notes,
     read_state,
     relationships,
     tutorial,
     user_guild_settings,
     user_settings,
 }

Removed the following methods:

- `Client::login_user`

Deprecated `Client::login_bot` in favour of `Client::login`.

Removed `client::LoginType`.

The following no longer take a `login_type` parameter:

- `Context::new`
- `Shard::new`

`Shard::sync_guilds` has been removed.

The `client::Error::{InvalidOperationAsBot, InvalidOperationAsUser}`
variants have been removed.

The following event handlers on `Client` have been removed:

- `on_friend_suggestion_create`
- `on_friend_suggestion_delete`
- `on_relationship_add`
- `on_relationship_remove`
- `on_user_guild_settings_update`
- `on_note_update`
- `on_user_settings_update`

The following `client::rest` functions have been removed:

- `ack_message`
- `edit_note`
- `get_user_connections`
- `search_channel_messages`
- `search_guild_messages`

The following `client::rest::ratelimiting::Route` variants have been
removed:

- `ChannelsIdMessagesSearch`
- `GuildsIdMessagesSearch`
- `UsersMeConnections`

The following fields on `ext::cache::Cache` have been removed:

- `guild_settings`
- `relationships`
- `settings`

while the following methods have also been removed:

- `update_with_relationship_add`
- `update_with_relationship_remove`
- `update_with_user_guild_settings_update`
- `update_with_user_note_update`
- `update_with_user_settings_update`

The following methods have been removed across models:

- `ChannelId::{ack, search}`
- `Channel::{ack, search}`
- `Group::{ack, search}`
- `GuildChannel::{ack, search}`
- `GuildId::{search, search_channels}`
- `Guild::{search, search_channels}`
- `Message::ack`
- `PartialGuild::{search, search_channels}`
- `PrivateChannel::{ack, search}`
- `UserId::{delete_note, edit_note}`
- `User::{delete_note, edit_note}`

The following events in `model::events` have been removed:

- `FriendSuggestionCreateEvent`
- `FriendSuggestionDeleteEvent`
- `MessageAckEvent`
- `RelationshipAddEvent`
- `RelationshipRemoveEvent`
- `UserGuildSettingsUpdateEvent`
- `UserNoteUpdateEvent`
- `UserSettingsUpdateEvent`

Consequently, the following variants on `model::event::Event` have been
removed:

- `FriendSuggestionCreate`
- `FriendSuggestionDelete`
- `MessageAdd`
- `RelationshipAdd`
- `RelationshipRemove`
- `UserGuildSettingUpdate`
- `UserNoteUpdate`
- `UserSettingsUpdate`

The `utils::builder::Search` search builder has been removed.

8 files changed, 23 insertions, 274 deletions

diff --git a/src/model/channel/attachment.rs b/src/model/channel/attachment.rs
index 387edaf..b6ce53d 100644
--- a/src/model/channel/attachment.rs
+++ b/src/model/channel/attachment.rs
@@ -28,7 +28,7 @@ impl Attachment {
     /// use std::path::Path;
     ///
     /// let token = env::var("DISCORD_TOKEN").expect("token in environment");
-    /// let mut client = Client::login_bot(&token);
+    /// let mut client = Client::login(&token);
     ///
     /// client.on_message(|_, message| {
     ///     for attachment in message.attachments {
diff --git a/src/model/channel/channel_id.rs b/src/model/channel/channel_id.rs
index 2d09367..7a2fb3a 100644
--- a/src/model/channel/channel_id.rs
+++ b/src/model/channel/channel_id.rs
@@ -1,24 +1,14 @@
 use serde_json::builder::ObjectBuilder;
 use std::fmt::{Display, Formatter, Result as FmtResult, Write as FmtWrite};
 use std::io::Read;
-use ::client::{CACHE, rest};
+use ::client::rest;
 use ::model::*;
-use ::utils::builder::{CreateMessage, EditChannel, GetMessages, Search};
+use ::utils::builder::{CreateMessage, EditChannel, GetMessages};
 
-impl ChannelId {
-    /// Marks a [`Channel`] as being read up to a certain [`Message`].
-    ///
-    /// Refer to the documentation for [`rest::ack_message`] for more
-    /// information.
-    ///
-    /// [`Channel`]: enum.Channel.html
-    /// [`Message`]: struct.Message.html
-    /// [`rest::ack_message`]: rest/fn.ack_message.html
-    #[inline]
-    pub fn ack<M: Into<MessageId>>(&self, message_id: M) -> Result<()> {
-        rest::ack_message(self.0, message_id.into().0)
-    }
+#[cfg(feature="cache")]
+use ::client::CACHE;
 
+impl ChannelId {
     /// Broadcasts that the current user is typing to a channel for the next 5
     /// seconds.
     ///
@@ -358,25 +348,6 @@ impl ChannelId {
         self.send_message(|m| m.content(content))
     }
 
-    /// Searches the channel's messages by providing query parameters via the
-    /// search builder.
-    ///
-    /// Refer to the documentation for the [`Search`] builder for restrictions
-    /// and defaults parameters, as well as potentially advanced usage.
-    ///
-    /// **Note**: Bot users can not search.
-    ///
-    /// # Examples
-    ///
-    /// Refer to the [`Search`] builder's documentation for examples,
-    /// specifically the section on [searching a channel][search channel].
-    ///
-    /// [`Search`]: ../utils/builder/struct.Search.html
-    #[inline]
-    pub fn search<F: FnOnce(Search) -> Search>(&self, f: F) -> Result<SearchResult> {
-        rest::search_channel_messages(self.0, f(Search::default()).0)
-    }
-
     /// Sends a file along with optional message contents. The filename _must_
     /// be specified.
     ///
diff --git a/src/model/channel/group.rs b/src/model/channel/group.rs
index 9d3335f..f287e9a 100644
--- a/src/model/channel/group.rs
+++ b/src/model/channel/group.rs
@@ -1,36 +1,11 @@
 use std::borrow::Cow;
 use std::fmt::Write as FmtWrite;
 use std::io::Read;
-use ::client::{CACHE, rest};
+use ::client::rest;
 use ::model::*;
-use ::utils::builder::{CreateMessage, GetMessages, Search};
+use ::utils::builder::{CreateMessage, GetMessages};
 
 impl Group {
-    /// Marks the group as being read up to a certain [`Message`].
-    ///
-    /// Refer to the documentation for [`rest::ack_message`] for more
-    /// information.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot
-    /// user.
-    ///
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsUser
-    /// [`Message`]: struct.Message.html
-    /// [`rest::ack_message`]: ../client/rest/fn.ack_message.html
-    pub fn ack<M: Into<MessageId>>(&self, message_id: M) -> Result<()> {
-        #[cfg(feature="cache")]
-        {
-            if CACHE.read().unwrap().user.bot {
-                return Err(Error::Client(ClientError::InvalidOperationAsBot));
-            }
-        }
-
-        self.channel_id.ack(message_id)
-    }
-
     /// Adds the given user to the group. If the user is already in the group,
     /// then nothing is done.
     ///
@@ -257,27 +232,6 @@ impl Group {
         self.channel_id.say(content)
     }
 
-    /// Performs a search request to the API for the group's channel's
-    /// [`Message`]s.
-    ///
-    /// Refer to the documentation for the [`Search`] builder for examples and
-    /// more information.
-    ///
-    /// **Note**: Bot users can not search.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot.
-    ///
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsBot
-    /// [`Message`]: struct.Message.html
-    /// [`Search`]: ../utils/builder/struct.Search.html
-    #[inline]
-    pub fn search<F: FnOnce(Search) -> Search>(&self, f: F) -> Result<SearchResult> {
-        self.channel_id.search(f)
-    }
-
     /// Sends a file along with optional message contents. The filename _must_
     /// be specified.
     ///
diff --git a/src/model/channel/guild_channel.rs b/src/model/channel/guild_channel.rs
index 677e77b..e4a84c7 100644
--- a/src/model/channel/guild_channel.rs
+++ b/src/model/channel/guild_channel.rs
@@ -2,37 +2,15 @@ use serde_json::builder::ObjectBuilder;
 use std::fmt::{Display, Formatter, Result as FmtResult};
 use std::io::Read;
 use std::mem;
-use ::client::{CACHE, rest};
+use ::client::rest;
 use ::internal::prelude::*;
 use ::model::*;
-use ::utils::builder::{CreateInvite, CreateMessage, EditChannel, GetMessages, Search};
+use ::utils::builder::{CreateInvite, CreateMessage, EditChannel, GetMessages};
 
-impl GuildChannel {
-    /// Marks the channel as being read up to a certain [`Message`].
-    ///
-    /// Refer to the documentation for [`rest::ack_message`] for more
-    /// information.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot
-    /// user.
-    ///
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsUser
-    /// [`Message`]: struct.Message.html
-    /// [`rest::ack_message`]: ../client/rest/fn.ack_message.html
-    pub fn ack<M: Into<MessageId>>(&self, message_id: M) -> Result<()> {
-        #[cfg(feature="cache")]
-        {
-            if CACHE.read().unwrap().user.bot {
-                return Err(Error::Client(ClientError::InvalidOperationAsBot));
-            }
-        }
-
-        rest::ack_message(self.id.0, message_id.into().0)
-    }
+#[cfg(feature="cache")]
+use ::client::CACHE;
 
+impl GuildChannel {
     /// Broadcasts to the channel that the current user is typing.
     ///
     /// For bots, this is a good indicator for long-running commands.
@@ -402,32 +380,6 @@ impl GuildChannel {
         self.id.say(content)
     }
 
-    /// Performs a search request for the channel's [`Message`]s.
-    ///
-    /// Refer to the documentation for the [`Search`] builder for examples and
-    /// more information.
-    ///
-    /// **Note**: Bot users can not search.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot.
-    ///
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsBot
-    /// [`Message`]: struct.Message.html
-    /// [`Search`]: ../utils/builder/struct.Search.html
-    pub fn search<F: FnOnce(Search) -> Search>(&self, f: F) -> Result<SearchResult> {
-        #[cfg(feature="cache")]
-        {
-            if CACHE.read().unwrap().user.bot {
-                return Err(Error::Client(ClientError::InvalidOperationAsBot));
-            }
-        }
-
-        self.id.search(f)
-    }
-
     /// Sends a file along with optional message contents. The filename _must_
     /// be specified.
     ///
diff --git a/src/model/channel/message.rs b/src/model/channel/message.rs
index 84d726d..709ce9a 100644
--- a/src/model/channel/message.rs
+++ b/src/model/channel/message.rs
@@ -1,37 +1,14 @@
 use serde_json::builder::ObjectBuilder;
 use std::mem;
 use ::constants;
-use ::client::{CACHE, rest};
+use ::client::rest;
 use ::model::*;
 use ::utils::builder::{CreateEmbed, CreateMessage};
 
-impl Message {
-    /// Marks the [`Channel`] as being read up to the message.
-    ///
-    /// Refer to the documentation for [`rest::ack_message`] for more
-    /// information.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot
-    /// user.
-    ///
-    /// [`Channel`]: enum.Channel.html
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsUser
-    /// [`Message`]: struct.Message.html
-    /// [`rest::ack_message`]: ../client/rest/fn.ack_message.html
-    pub fn ack<M: Into<MessageId>>(&self) -> Result<()> {
-        #[cfg(feature="cache")]
-        {
-            if CACHE.read().unwrap().user.bot {
-                return Err(Error::Client(ClientError::InvalidOperationAsBot));
-            }
-        }
-
-        self.channel_id.ack(self.id)
-    }
+#[cfg(feature="cache")]
+use ::client::CACHE;
 
+impl Message {
     /// Deletes the message.
     ///
     /// **Note**: The logged in user must either be the author of the message or
diff --git a/src/model/channel/mod.rs b/src/model/channel/mod.rs
index ff12084..3ea765a 100644
--- a/src/model/channel/mod.rs
+++ b/src/model/channel/mod.rs
@@ -18,37 +18,10 @@ pub use self::reaction::*;
 
 use std::fmt::{Display, Formatter, Result as FmtResult};
 use std::io::Read;
-use ::client::CACHE;
 use ::model::*;
-use ::utils::builder::{CreateMessage, GetMessages, Search};
+use ::utils::builder::{CreateMessage, GetMessages};
 
 impl Channel {
-    /// Marks the channel as being read up to a certain [`Message`].
-    ///
-    /// Refer to the documentation for [`rest::ack_message`] for more
-    /// information.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot
-    /// user.
-    ///
-    /// [`Channel`]: enum.Channel.html
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsUser
-    /// [`Message`]: struct.Message.html
-    /// [`rest::ack_message`]: ../client/rest/fn.ack_message.html
-    pub fn ack<M: Into<MessageId>>(&self, message_id: M) -> Result<()> {
-        #[cfg(feature="cache")]
-        {
-            if CACHE.read().unwrap().user.bot {
-                return Err(Error::Client(ClientError::InvalidOperationAsBot));
-            }
-        }
-
-        self.id().ack(message_id)
-    }
-
     /// React to a [`Message`] with a custom [`Emoji`] or unicode character.
     ///
     /// [`Message::react`] may be a more suited method of reacting in most
@@ -273,34 +246,6 @@ impl Channel {
         self.id().say(content)
     }
 
-    /// Performs a search request to the API for the inner channel's
-    /// [`Message`]s.
-    ///
-    /// Refer to the documentation for the [`Search`] builder for examples and
-    /// more information.
-    ///
-    /// **Note**: Bot users can not search.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot.
-    ///
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsBot
-    /// [`Message`]: struct.Message.html
-    /// [`Search`]: ../utils/builder/struct.Search.html
-    pub fn search<F>(&self, f: F) -> Result<SearchResult>
-        where F: FnOnce(Search) -> Search {
-        #[cfg(feature="cache")]
-        {
-            if CACHE.read().unwrap().user.bot {
-                return Err(Error::Client(ClientError::InvalidOperationAsBot));
-            }
-        }
-
-        self.id().search(f)
-    }
-
     /// Sends a file along with optional message contents. The filename _must_
     /// be specified.
     ///
diff --git a/src/model/channel/private_channel.rs b/src/model/channel/private_channel.rs
index ae64d7e..8ce520c 100644
--- a/src/model/channel/private_channel.rs
+++ b/src/model/channel/private_channel.rs
@@ -1,35 +1,9 @@
 use std::fmt::{Display, Formatter, Result as FmtResult};
 use std::io::Read;
-use ::client::CACHE;
 use ::model::*;
-use ::utils::builder::{CreateMessage, GetMessages, Search};
+use ::utils::builder::{CreateMessage, GetMessages};
 
 impl PrivateChannel {
-    /// Marks the channel as being read up to a certain [`Message`].
-    ///
-    /// Refer to the documentation for [`rest::ack_message`] for more
-    /// information.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot
-    /// user.
-    ///
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsUser
-    /// [`Message`]: struct.Message.html
-    /// [`rest::ack_message`]: ../client/rest/fn.ack_message.html
-    pub fn ack<M: Into<MessageId>>(&self, message_id: M) -> Result<()> {
-        #[cfg(feature="cache")]
-        {
-            if CACHE.read().unwrap().user.bot {
-                return Err(Error::Client(ClientError::InvalidOperationAsBot));
-            }
-        }
-
-        self.id.ack(message_id)
-    }
-
     /// Broadcasts that the current user is typing to the recipient.
     pub fn broadcast_typing(&self) -> Result<()> {
         self.id.broadcast_typing()
@@ -219,33 +193,6 @@ impl PrivateChannel {
         self.id.say(content)
     }
 
-    /// Performs a search request to the API for the channel's [`Message`]s.
-    ///
-    /// Refer to the documentation for the [`Search`] builder for examples and
-    /// more information.
-    ///
-    /// **Note**: Bot users can not search.
-    ///
-    /// # Errors
-    ///
-    /// If the `cache` is enabled, returns a
-    /// [`ClientError::InvalidOperationAsBot`] if the current user is a bot.
-    ///
-    /// [`ClientError::InvalidOperationAsBot`]: ../client/enum.ClientError.html#variant.InvalidOperationAsBot
-    /// [`Message`]: struct.Message.html
-    /// [`Search`]: ../utils/builder/struct.Search.html
-    pub fn search<F>(&self, f: F) -> Result<SearchResult>
-        where F: FnOnce(Search) -> Search {
-        #[cfg(feature="cache")]
-        {
-            if CACHE.read().unwrap().user.bot {
-                return Err(Error::Client(ClientError::InvalidOperationAsBot));
-            }
-        }
-
-        self.id.search(f)
-    }
-
     /// Sends a file along with optional message contents. The filename _must_
     /// be specified.
     ///
diff --git a/src/model/channel/reaction.rs b/src/model/channel/reaction.rs
index eaeb2cc..aa4f339 100644
--- a/src/model/channel/reaction.rs
+++ b/src/model/channel/reaction.rs
@@ -1,8 +1,11 @@
 use std::fmt::{Display, Formatter, Result as FmtResult, Write as FmtWrite};
-use ::client::{CACHE, rest};
+use ::client::rest;
 use ::internal::prelude::*;
 use ::model::*;
 
+#[cfg(feature="cache")]
+use ::client::CACHE;
+
 impl Reaction {
     /// Deletes the reaction, but only if the current user is the user who made
     /// the reaction or has permission to.