Restructure modules

Modules are now separated into a fashion where the library can be used
for most use cases, without needing to compile the rest.

The core of serenity, with no features enabled, contains only the
struct (model) definitions, constants, and prelude. Models do not have
most functions compiled in, as that is separated into the `model`
feature.

The `client` module has been split into 3 modules: `client`, `gateway`,
and `http`.

`http` contains functions to interact with the REST API. `gateway`
contains the Shard to interact with the gateway, requiring `http` for
retrieving the gateway URL. `client` requires both of the other features
and acts as an abstracted interface over both the gateway and REST APIs,
handling the event loop.

The `builder` module has been separated from `utils`, and can now be
optionally compiled in. It and the `http` feature are required by the
`model` feature due to a large number of methods requiring access to
them.

`utils` now contains a number of utilities, such as the Colour struct, the
`MessageBuilder`, and mention parsing functions.

Each of the original `ext` modules are still featured, with `cache` not
requiring any feature to be enabled, `framework` requiring the `client`,
`model`, and `utils`, and `voice` requiring `gateway`.

In total the features and their requirements are:

- `builder`: none
- `cache`: none
- `client`: `gateway`, `http`
- `framework`: `client`, `model`, `utils`
- `gateway`: `http`
- `http`: none
- `model`: `builder`, `http`
- `utils`: none
- `voice`: `gateway`

The default features are `builder`, `cache`, `client`, `framework`,
`gateway`, `model`, `http`, and `utils`.

To help with forwards compatibility, modules have been re-exported from
their original locations.

1 files changed, 20 insertions, 16 deletions

diff --git a/src/model/channel/group.rs b/src/model/channel/group.rs
index bf87590..adafdc8 100644
--- a/src/model/channel/group.rs
+++ b/src/model/channel/group.rs
@@ -1,9 +1,12 @@
 use std::borrow::Cow;
 use std::fmt::Write as FmtWrite;
 use std::io::Read;
-use ::client::rest;
 use ::model::*;
-use ::utils::builder::{CreateMessage, GetMessages};
+
+#[cfg(feature="model")]
+use ::builder::{CreateMessage, GetMessages};
+#[cfg(feature="model")]
+use ::http;
 
 /// A group channel - potentially including other [`User`]s - separate from a
 /// [`Guild`].
@@ -30,16 +33,17 @@ pub struct Group {
     pub recipients: HashMap<UserId, Arc<RwLock<User>>>,
 }
 
+#[cfg(feature="model")]
 impl Group {
     /// Adds the given user to the group. If the user is already in the group,
     /// then nothing is done.
     ///
-    /// Refer to [`rest::add_group_recipient`] for more information.
+    /// Refer to [`http::add_group_recipient`] for more information.
     ///
     /// **Note**: Groups have a limit of 10 recipients, including the current
     /// user.
     ///
-    /// [`rest::add_group_recipient`]: ../client/rest/fn.add_group_recipient.html
+    /// [`http::add_group_recipient`]: ../http/fn.add_group_recipient.html
     pub fn add_recipient<U: Into<UserId>>(&self, user: U) -> Result<()> {
         let user = user.into();
 
@@ -48,7 +52,7 @@ impl Group {
             return Ok(());
         }
 
-        rest::add_group_recipient(self.channel_id.0, user.0)
+        http::add_group_recipient(self.channel_id.0, user.0)
     }
 
     /// Broadcasts that the current user is typing in the group.
@@ -129,14 +133,14 @@ impl Group {
     ///
     /// # Errors
     ///
-    /// Returns a [`ClientError::MessageTooLong`] if the content of the message
+    /// Returns a [`ModelError::MessageTooLong`] if the content of the message
     /// is over the [`the limit`], containing the number of unicode code points
     /// over the limit.
     ///
-    /// [`ClientError::MessageTooLong`]: ../client/enum.ClientError.html#variant.MessageTooLong
-    /// [`CreateMessage`]: ../utils/builder/struct.CreateMessage.html
+    /// [`ModelError::MessageTooLong`]: enum.ModelError.html#variant.MessageTooLong
+    /// [`CreateMessage`]: ../builder/struct.CreateMessage.html
     /// [`Message`]: struct.Message.html
-    /// [`the limit`]: ../utils/builder/struct.CreateMessage.html#method.content
+    /// [`the limit`]: ../builder/struct.CreateMessage.html#method.content
     #[inline]
     pub fn edit_message<F, M>(&self, message_id: M, f: F) -> Result<Message>
         where F: FnOnce(CreateMessage) -> CreateMessage, M: Into<MessageId> {
@@ -165,7 +169,7 @@ impl Group {
     /// Leaves the group.
     #[inline]
     pub fn leave(&self) -> Result<Group> {
-        rest::leave_group(self.channel_id.0)
+        http::leave_group(self.channel_id.0)
     }
 
     /// Gets a message from the channel.
@@ -252,19 +256,19 @@ impl Group {
             return Ok(());
         }
 
-        rest::remove_group_recipient(self.channel_id.0, user.0)
+        http::remove_group_recipient(self.channel_id.0, user.0)
     }
 
     /// Sends a message with just the given message content in the channel.
     ///
     /// # Errors
     ///
-    /// Returns a [`ClientError::MessageTooLong`] if the content of the message
+    /// Returns a [`ModelError::MessageTooLong`] if the content of the message
     /// is over the above limit, containing the number of unicode code points
     /// over the limit.
     ///
     /// [`ChannelId`]: ../model/struct.ChannelId.html
-    /// [`ClientError::MessageTooLong`]: enum.ClientError.html#variant.MessageTooLong
+    /// [`ModelError::MessageTooLong`]: enum.ModelError.html#variant.MessageTooLong
     #[inline]
     pub fn say(&self, content: &str) -> Result<Message> {
         self.channel_id.say(content)
@@ -282,11 +286,11 @@ impl Group {
     /// # Errors
     ///
     /// If the content of the message is over the above limit, then a
-    /// [`ClientError::MessageTooLong`] will be returned, containing the number
+    /// [`ModelError::MessageTooLong`] will be returned, containing the number
     /// of unicode code points over the limit.
     ///
     /// [`ChannelId::send_file`]: struct.ChannelId.html#method.send_file
-    /// [`ClientError::MessageTooLong`]: ../client/enum.ClientError.html#variant.MessageTooLong
+    /// [`ModelError::MessageTooLong`]: enum.ModelError.html#variant.MessageTooLong
     /// [Attach Files]: permissions/constant.ATTACH_FILES.html
     /// [Send Messages]: permissions/constant.SEND_MESSAGES.html
     pub fn send_file<F, R>(&self, file: R, filename: &str, f: F) -> Result<Message>
@@ -301,7 +305,7 @@ impl Group {
     ///
     /// **Note**: Requires the [Send Messages] permission.
     ///
-    /// [`CreateMessage`]: ../utils/builder/struct.CreateMessage.html
+    /// [`CreateMessage`]: ../builder/struct.CreateMessage.html
     /// [Send Messages]: permissions/constant.SEND_MESSAGES.html
     #[inline]
     pub fn send_message<F: FnOnce(CreateMessage) -> CreateMessage>(&self, f: F) -> Result<Message> {