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, 10 insertions, 3 deletions

diff --git a/src/model/misc.rs b/src/model/misc.rs
index 5cf3a91..4da3c01 100644
--- a/src/model/misc.rs
+++ b/src/model/misc.rs
@@ -1,6 +1,8 @@
 use std::result::Result as StdResult;
 use std::str::FromStr;
 use super::*;
+
+#[cfg(feature="utils")]
 use ::utils;
 
 /// Allows something - such as a channel or role - to be mentioned in a message.
@@ -68,7 +70,7 @@ impl Mentionable for User {
     }
 }
 
-#[cfg(feature="cache")]
+#[cfg(all(feature="cache", feature="utils"))]
 impl FromStr for User {
     type Err = ();
 
@@ -85,6 +87,7 @@ impl FromStr for User {
     }
 }
 
+#[cfg(all(feature="model", feature="utils"))]
 impl FromStr for UserId {
     type Err = ();
 
@@ -93,7 +96,7 @@ impl FromStr for UserId {
     }
 }
 
-#[cfg(feature="cache")]
+#[cfg(all(feature="cache", feature="utils"))]
 impl FromStr for Role {
     type Err = ();
 
@@ -110,6 +113,7 @@ impl FromStr for Role {
     }
 }
 
+#[cfg(all(feature="model", feature="utils"))]
 impl FromStr for RoleId {
     type Err = ();
 
@@ -128,6 +132,7 @@ pub struct EmojiIdentifier {
     pub name: String,
 }
 
+#[cfg(all(feature="model", feature="utils"))]
 impl EmojiIdentifier {
     /// Generates a URL to the emoji's image.
     #[inline]
@@ -136,6 +141,7 @@ impl EmojiIdentifier {
     }
 }
 
+#[cfg(all(feature="model", feature="utils"))]
 impl FromStr for EmojiIdentifier {
     type Err = ();
 
@@ -144,6 +150,7 @@ impl FromStr for EmojiIdentifier {
     }
 }
 
+#[cfg(all(feature="model", feature="utils"))]
 impl FromStr for ChannelId {
     type Err = ();
 
@@ -152,7 +159,7 @@ impl FromStr for ChannelId {
     }
 }
 
-#[cfg(feature="cache")]
+#[cfg(all(feature="cache", feature="model", feature="utils"))]
 impl FromStr for Channel {
     type Err = ();