Break up the model module

The `model` module has historically been one giant module re-exporting
all of the model types, which is somewhere around 100 types. This can be
a lot to look at for a new user and somewhat overwhelming, especially
with a large number of fine-grained imports from the module.

The module is now neatly split up into submodules, mostly like it has
been internally since the early versions of the library. The submodules
are:

- application
- channel
- error
- event
- gateway
- guild
- id
- invite
- misc
- permissions
- prelude
- user
- voice
- webhook

Each submodule contains types that are "owned" by the module. For
example, the `guild` submodule contains, but not limited to, Emoji,
AuditLogsEntry, Role, and Member. `channel` contains, but not limited
to, Attachment, Embed, Message, and Reaction.

Upgrade path:

Instead of glob importing the models via `use serenity::model::*;`,
instead glob import via the prelude:

```rust
use serenity::model::prelude::*;
```

Instead of importing from the root model module:

```rust
use serenity::model::{Guild, Message, OnlineStatus, Role, User};
```

instead import from the submodules like so:

```rust
use serenity::model::channel::Message;
use serenity::model::guild::{Guild, Role};
use serenity::model::user::{OnlineStatus, User};
```

8 files changed, 27 insertions, 20 deletions

diff --git a/src/framework/mod.rs b/src/framework/mod.rs
index c5ddb04..9f72dc6 100644
--- a/src/framework/mod.rs
+++ b/src/framework/mod.rs
@@ -61,11 +61,11 @@ pub mod standard;
 pub use self::standard::StandardFramework;
 
 use client::Context;
-use model::Message;
+use model::channel::Message;
 use threadpool::ThreadPool;
 
 #[cfg(feature = "standard_framework")]
-use model::UserId;
+use model::id::UserId;
 
 /// This trait allows for serenity to either use its builtin framework, or yours.
 pub trait Framework {
diff --git a/src/framework/standard/buckets.rs b/src/framework/standard/buckets.rs
index 60316b1..c29805f 100644
--- a/src/framework/standard/buckets.rs
+++ b/src/framework/standard/buckets.rs
@@ -1,6 +1,6 @@
 use chrono::Utc;
 use client::Context;
-use model::{ChannelId, GuildId, UserId};
+use model::id::{ChannelId, GuildId, UserId};
 use std::collections::HashMap;
 use std::default::Default;
 
diff --git a/src/framework/standard/command.rs b/src/framework/standard/command.rs
index d010f92..be0196c 100644
--- a/src/framework/standard/command.rs
+++ b/src/framework/standard/command.rs
@@ -1,5 +1,6 @@
 use client::Context;
-use model::{Message, Permissions};
+use model::channel::Message;
+use model::Permissions;
 use std::collections::HashMap;
 use std::fmt;
 use std::fmt::{Debug, Formatter};
diff --git a/src/framework/standard/configuration.rs b/src/framework/standard/configuration.rs
index 23148e3..d54a821 100644
--- a/src/framework/standard/configuration.rs
+++ b/src/framework/standard/configuration.rs
@@ -1,6 +1,7 @@
 use client::Context;
 use http;
-use model::{GuildId, Message, UserId};
+use model::channel::Message;
+use model::id::{GuildId, UserId};
 use std::collections::HashSet;
 use std::default::Default;
 use super::command::PrefixCheck;
@@ -101,7 +102,7 @@ impl Configuration {
     /// #
     /// # impl EventHandler for Handler {}
     /// # let mut client = Client::new("token", Handler).unwrap();
-    /// use serenity::model::GuildId;
+    /// use serenity::model::id::GuildId;
     /// use serenity::framework::StandardFramework;
     ///
     /// client.with_framework(StandardFramework::new().configure(|c| c
@@ -126,7 +127,7 @@ impl Configuration {
     /// #
     /// # impl EventHandler for Handler {}
     /// # let mut client = Client::new("token", Handler).unwrap();
-    /// use serenity::model::UserId;
+    /// use serenity::model::id::UserId;
     /// use serenity::framework::StandardFramework;
     ///
     /// client.with_framework(StandardFramework::new().configure(|c| c
@@ -287,7 +288,7 @@ impl Configuration {
     /// #
     /// # impl EventHandler for Handler {}
     /// # let mut client = Client::new("token", Handler).unwrap();
-    /// use serenity::model::UserId;
+    /// use serenity::model::id::UserId;
     /// use serenity::framework::StandardFramework;
     ///
     /// client.with_framework(StandardFramework::new().configure(|c| c
@@ -302,7 +303,7 @@ impl Configuration {
     /// #
     /// # impl EventHandler for Handler {}
     /// # let mut client = Client::new("token", Handler).unwrap();
-    /// use serenity::model::UserId;
+    /// use serenity::model::id::UserId;
     /// use std::collections::HashSet;
     /// use serenity::framework::StandardFramework;
     ///
diff --git a/src/framework/standard/create_command.rs b/src/framework/standard/create_command.rs
index 0df649d..6450b64 100644
--- a/src/framework/standard/create_command.rs
+++ b/src/framework/standard/create_command.rs
@@ -1,7 +1,8 @@
 pub use super::{Args, Command, CommandGroup, CommandOptions, CommandError};
 
 use client::Context;
-use model::{Message, Permissions};
+use model::channel::Message;
+use model::Permissions;
 use std::sync::Arc;
 
 pub enum FnOrCommand {
@@ -50,7 +51,7 @@ impl CreateCommand {
     ///     CommandError,
     ///     StandardFramework,
     /// };
-    /// use serenity::model::Message;
+    /// use serenity::model::channel::Message;
     /// use std::env;
     ///
     /// let token = env::var("DISCORD_TOKEN").unwrap();
diff --git a/src/framework/standard/create_group.rs b/src/framework/standard/create_group.rs
index 77fb348..986207a 100644
--- a/src/framework/standard/create_group.rs
+++ b/src/framework/standard/create_group.rs
@@ -5,7 +5,8 @@ pub use super::create_command::{CreateCommand, FnOrCommand};
 pub use super::Args;
 
 use client::Context;
-use model::{Message, Permissions};
+use model::channel::Message;
+use model::Permissions;
 use std::sync::Arc;
 
 /// Used to create command groups
diff --git a/src/framework/standard/help_commands.rs b/src/framework/standard/help_commands.rs
index b2fc9f5..85debc4 100644
--- a/src/framework/standard/help_commands.rs
+++ b/src/framework/standard/help_commands.rs
@@ -25,7 +25,8 @@
 
 use client::Context;
 use framework::standard::{has_correct_roles, has_correct_permissions};
-use model::{ChannelId, Message};
+use model::channel::Message;
+use model::id::ChannelId;
 use std::collections::HashMap;
 use std::sync::Arc;
 use std::fmt::Write;
diff --git a/src/framework/standard/mod.rs b/src/framework/standard/mod.rs
index 6f7e180..576f820 100644
--- a/src/framework/standard/mod.rs
+++ b/src/framework/standard/mod.rs
@@ -21,8 +21,10 @@ pub use self::create_group::CreateGroup;
 
 use client::Context;
 use internal::RwLockExt;
-use model::{ChannelId, GuildId, Guild, Member, Message, UserId};
-use model::permissions::Permissions;
+use model::channel::Message;
+use model::guild::{Guild, Member};
+use model::id::{ChannelId, GuildId, UserId};
+use model::Permissions;
 use self::command::{AfterHook, BeforeHook};
 use std::collections::HashMap;
 use std::default::Default;
@@ -33,7 +35,7 @@ use threadpool::ThreadPool;
 #[cfg(feature = "cache")]
 use client::CACHE;
 #[cfg(feature = "cache")]
-use model::Channel;
+use model::channel::Channel;
 
 /// A macro to generate "named parameters". This is useful to avoid manually
 /// using the "arguments" parameter and manually parsing types.
@@ -77,7 +79,7 @@ macro_rules! command {
         impl $crate::framework::standard::Command for $fname {
             #[allow(unreachable_code, unused_mut)]
             fn execute(&self, mut $c: &mut $crate::client::Context,
-                      _: &$crate::model::Message,
+                      _: &$crate::model::channel::Message,
                       _: $crate::framework::standard::Args)
                       -> ::std::result::Result<(), $crate::framework::standard::CommandError> {
 
@@ -94,7 +96,7 @@ macro_rules! command {
         impl $crate::framework::standard::Command for $fname {
             #[allow(unreachable_code, unused_mut)]
             fn execute(&self, mut $c: &mut $crate::client::Context,
-                      $m: &$crate::model::Message,
+                      $m: &$crate::model::channel::Message,
                       _: $crate::framework::standard::Args)
                       -> ::std::result::Result<(), $crate::framework::standard::CommandError> {
 
@@ -111,7 +113,7 @@ macro_rules! command {
         impl $crate::framework::standard::Command for $fname {
             #[allow(unreachable_code, unused_mut)]
             fn execute(&self, mut $c: &mut $crate::client::Context,
-                      $m: &$crate::model::Message,
+                      $m: &$crate::model::channel::Message,
                       mut $a: $crate::framework::standard::Args)
                       -> ::std::result::Result<(), $crate::framework::standard::CommandError> {
 
@@ -1098,4 +1100,4 @@ impl fmt::Display for HelpBehaviour {
            HelpBehaviour::Nothing => write!(f, "HelBehaviour::Nothing"),
        }
     }
-}
\ No newline at end of file
+}