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};
```

1 files changed, 9 insertions, 7 deletions

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
+}