More config for CreateCommand, add various methods

Adds multiple configurations to the command builder, and adds methods
to various structs.

Context::get_current_user is a shortcut to retrieve the current user
from the cache.

Message::get_member retrieves the member object of the message, if sent
in a guild. Message::is_private checks if the message was sent in a
Group or PrivateChannel.

User::member retrieves the user's member object in a guild by Id;

Adds 6 configurations to the command builder:

- dm_only: whether the command can only be used in direct messages;
- guild_only: whether the command can only be used in guilds;
- help_available: whether the command should be displayed in the help
  list;
- max_args: specify the maximum number of arguments a command must be
  given;
- min_args: specify the minimum number of arguments a command must be
  given;
- required_permissions: the permissions a member must have to be able
  to use the command;

6 files changed, 47 insertions, 38 deletions

diff --git a/src/client/context.rs b/src/client/context.rs
index eb7246b..e646ec6 100644
--- a/src/client/context.rs
+++ b/src/client/context.rs
@@ -22,7 +22,7 @@ use ::internal::prelude::*;
 use ::model::*;
 use ::utils;
 
-#[cfg(feature = "cache")]
+#[cfg(feature="cache")]
 use super::CACHE;
 
 /// The context is a general utility struct provided on event dispatches, which
@@ -1077,6 +1077,15 @@ impl Context {
         Ok(channels)
     }
 
+    /// Gets information about the current user.
+    ///
+    /// Note this is shorthand for retrieving the current user through the
+    /// cache, and will perform a clone.
+    #[cfg(all(feature = "cache", feature = "methods"))]
+    pub fn get_current_user(&self) -> CurrentUser {
+        CACHE.read().unwrap().user.clone()
+    }
+
     /// Gets an [`Guild`]'s emoji by Id.
     ///
     /// Requires the [Manage Emojis] permission.
diff --git a/src/client/dispatch.rs b/src/client/dispatch.rs
index 7b0439d..5f61ea9 100644
--- a/src/client/dispatch.rs
+++ b/src/client/dispatch.rs
@@ -11,7 +11,7 @@ use ::model::{ChannelId, Message};
 #[cfg(feature="framework")]
 use ::ext::framework::Framework;
 
-#[cfg(feature = "cache")]
+#[cfg(feature="cache")]
 use super::CACHE;
 
 macro_rules! handler {
diff --git a/src/client/event_store.rs b/src/client/event_store.rs
index e2ddf94..7cc7e81 100644
--- a/src/client/event_store.rs
+++ b/src/client/event_store.rs
@@ -14,7 +14,7 @@ use ::model::event::{
 };
 use ::model::*;
 
-#[cfg(not(feature = "cache"))]
+#[cfg(not(feature="cache"))]
 use ::model::event::{
     CallUpdateEvent,
     GuildMemberUpdateEvent,
@@ -43,13 +43,13 @@ use ::model::event::{
 #[derive(Default)]
 pub struct EventStore {
     pub on_call_create: Option<Arc<Fn(Context, Call) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_call_delete: Option<Arc<Fn(Context, ChannelId, Option<Call>) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_call_delete: Option<Arc<Fn(Context, ChannelId) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_call_update: Option<Arc<Fn(Context, Option<Call>, Option<Call>) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_call_update: Option<Arc<Fn(Context, CallUpdateEvent) + Send + Sync + 'static>>,
     pub on_channel_create: Option<Arc<Fn(Context, Channel) + Send + Sync + 'static>>,
     pub on_channel_delete: Option<Arc<Fn(Context, Channel) + Send + Sync + 'static>>,
@@ -57,45 +57,45 @@ pub struct EventStore {
     pub on_channel_pins_update: Option<Arc<Fn(Context, ChannelPinsUpdateEvent) + Send + Sync + 'static>>,
     pub on_channel_recipient_addition: Option<Arc<Fn(Context, ChannelId, User) + Send + Sync + 'static>>,
     pub on_channel_recipient_removal: Option<Arc<Fn(Context, ChannelId, User) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_channel_update: Option<Arc<Fn(Context, Option<Channel>, Channel) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_channel_update: Option<Arc<Fn(Context, Channel) + Send + Sync + 'static>>,
     pub on_friend_suggestion_create: Option<Arc<Fn(Context, User, Vec<SuggestionReason>) + Send + Sync + 'static>>,
     pub on_friend_suggestion_delete: Option<Arc<Fn(Context, UserId) + Send + Sync + 'static>>,
     pub on_guild_ban_addition: Option<Arc<Fn(Context, GuildId, User) + Send + Sync + 'static>>,
     pub on_guild_ban_removal: Option<Arc<Fn(Context, GuildId, User) + Send + Sync + 'static>>,
     pub on_guild_create: Option<Arc<Fn(Context, Guild) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_guild_delete: Option<Arc<Fn(Context, PartialGuild, Option<Guild>) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_guild_delete: Option<Arc<Fn(Context, PartialGuild) + Send + Sync + 'static>>,
     pub on_guild_emojis_update: Option<Arc<Fn(Context, GuildId, HashMap<EmojiId, Emoji>) + Send + Sync + 'static>>,
     pub on_guild_integrations_update: Option<Arc<Fn(Context, GuildId) + Send + Sync + 'static>>,
     pub on_guild_member_addition: Option<Arc<Fn(Context, GuildId, Member) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_guild_member_removal: Option<Arc<Fn(Context, GuildId, User, Option<Member>) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_guild_member_removal: Option<Arc<Fn(Context, GuildId, User) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_guild_member_update: Option<Arc<Fn(Context, Option<Member>, Member) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_guild_member_update: Option<Arc<Fn(Context, GuildMemberUpdateEvent) + Send + Sync + 'static>>,
     pub on_guild_members_chunk: Option<Arc<Fn(Context, GuildId, HashMap<UserId, Member>) + Send + Sync + 'static>>,
     pub on_guild_role_create: Option<Arc<Fn(Context, GuildId, Role) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_guild_role_delete: Option<Arc<Fn(Context, GuildId, RoleId, Option<Role>) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_guild_role_delete: Option<Arc<Fn(Context, GuildId, RoleId) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_guild_role_update: Option<Arc<Fn(Context, GuildId, Option<Role>, Role) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_guild_role_update: Option<Arc<Fn(Context, GuildId, Role) + Send + Sync + 'static>>,
     pub on_guild_sync: Option<Arc<Fn(Context, GuildSyncEvent) + Send + Sync + 'static>>,
     pub on_guild_unavailable: Option<Arc<Fn(Context, GuildId) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_guild_update: Option<Arc<Fn(Context, Option<Guild>, PartialGuild) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_guild_update: Option<Arc<Fn(Context, PartialGuild) + Send + Sync + 'static>>,
     pub on_message: Option<Arc<Fn(Context, Message) + Send + Sync + 'static>>,
     pub on_message_ack: Option<Arc<Fn(Context, ChannelId, Option<MessageId>) + Send + Sync + 'static>>,
@@ -105,9 +105,9 @@ pub struct EventStore {
     pub on_reaction_remove: Option<Arc<Fn(Context, Reaction) + Send + Sync + 'static>>,
     pub on_reaction_remove_all: Option<Arc<Fn(Context, ChannelId, MessageId) + Send + Sync + 'static>>,
     pub on_message_update: Option<Arc<Fn(Context, MessageUpdateEvent) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_note_update: Option<Arc<Fn(Context, UserId, Option<String>, String) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_note_update: Option<Arc<Fn(Context, UserId, String) + Send + Sync + 'static>>,
     pub on_presence_replace: Option<Arc<Fn(Context, Vec<Presence>) + Send + Sync + 'static>>,
     pub on_presence_update: Option<Arc<Fn(Context, PresenceUpdateEvent) + Send + Sync + 'static>>,
@@ -117,17 +117,17 @@ pub struct EventStore {
     pub on_resume: Option<Arc<Fn(Context, ResumedEvent) + Send + Sync + 'static>>,
     pub on_typing_start: Option<Arc<Fn(Context, TypingStartEvent) + Send + Sync + 'static>>,
     pub on_unknown: Option<Arc<Fn(Context, String, BTreeMap<String, Value>) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_user_guild_settings_update: Option<Arc<Fn(Context, Option<UserGuildSettings>, UserGuildSettings) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_user_guild_settings_update: Option<Arc<Fn(Context, UserGuildSettings) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_user_update: Option<Arc<Fn(Context, CurrentUser, CurrentUser) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_user_update: Option<Arc<Fn(Context, CurrentUser) + Send + Sync + 'static>>,
-    #[cfg(feature = "cache")]
+    #[cfg(feature="cache")]
     pub on_user_settings_update: Option<Arc<Fn(Context, UserSettings, UserSettings) + Send + Sync + 'static>>,
-    #[cfg(not(feature = "cache"))]
+    #[cfg(not(feature="cache"))]
     pub on_user_settings_update: Option<Arc<Fn(Context, UserSettingsUpdateEvent) + Send + Sync + 'static>>,
     pub on_voice_server_update: Option<Arc<Fn(Context, VoiceServerUpdateEvent) + Send + Sync + 'static>>,
     pub on_voice_state_update: Option<Arc<Fn(Context, Option<GuildId>, VoiceState) + Send + Sync + 'static>>,
diff --git a/src/client/gateway/prep.rs b/src/client/gateway/prep.rs
index 3844a8d..4602ea6 100644
--- a/src/client/gateway/prep.rs
+++ b/src/client/gateway/prep.rs
@@ -80,12 +80,12 @@ pub fn identify(token: &str, shard_info: Option<[u8; 2]>) -> Value {
         .build()
 }
 
-#[cfg(not(feature = "debug"))]
+#[cfg(not(feature="debug"))]
 pub fn identify_compression(object: ObjectBuilder) -> ObjectBuilder {
     object.insert("compression", true)
 }
 
-#[cfg(feature = "debug")]
+#[cfg(feature="debug")]
 pub fn identify_compression(object: ObjectBuilder) -> ObjectBuilder {
     object.insert("compression", false)
 }
diff --git a/src/client/gateway/shard.rs b/src/client/gateway/shard.rs
index 232d2c3..c026f0c 100644
--- a/src/client/gateway/shard.rs
+++ b/src/client/gateway/shard.rs
@@ -69,7 +69,7 @@ pub struct Shard {
     ws_url: String,
     /// The voice connections that this Shard is responsible for. The Shard will
     /// update the voice connections' states.
-    #[cfg(feature = "voice")]
+    #[cfg(feature="voice")]
     pub manager: VoiceManager,
 }
 
diff --git a/src/client/mod.rs b/src/client/mod.rs
index 843bbfe..c9a9c65 100644
--- a/src/client/mod.rs
+++ b/src/client/mod.rs
@@ -61,20 +61,20 @@ use ::model::event::{
 };
 use ::model::*;
 
-#[cfg(feature = "framework")]
+#[cfg(feature="framework")]
 use ::ext::framework::Framework;
 
-#[cfg(feature = "cache")]
+#[cfg(feature="cache")]
 use ::ext::cache::Cache;
 
-#[cfg(not(feature = "cache"))]
+#[cfg(not(feature="cache"))]
 use ::model::event::{
     CallUpdateEvent,
     GuildMemberUpdateEvent,
     UserSettingsUpdateEvent,
 };
 
-#[cfg(feature = "cache")]
+#[cfg(feature="cache")]
 lazy_static! {
     /// A mutable and lazily-initialized static binding. It can be accessed
     /// across any function and in any context.
@@ -841,7 +841,7 @@ impl Client {
     }
 }
 
-#[cfg(feature = "cache")]
+#[cfg(feature="cache")]
 impl Client {
     /// Attaches a handler for when a [`CallDelete`] is received.
     ///
@@ -1003,7 +1003,7 @@ impl Client {
     }
 }
 
-#[cfg(not(feature = "cache"))]
+#[cfg(not(feature="cache"))]
 impl Client {
     /// Attaches a handler for when a [`CallDelete`] is received.
     ///