Update doctests for Context changes

Due to the Context having many methods removed, the doctests were
failing.

Update the doctests to use alternative methods to accomplish the same.

Example:

Before:
```rust
context.say("hi");
```

After:
```rust
message.channel_id.say("hi")
```

11 files changed, 40 insertions, 41 deletions

diff --git a/src/client/mod.rs b/src/client/mod.rs
index d0593fe..0da4b0e 100644
--- a/src/client/mod.rs
+++ b/src/client/mod.rs
@@ -138,7 +138,7 @@ lazy_static! {
 ///
 /// client.on_message(|context, message| {
 ///     if message.content == "!ping" {
-///         context.say("Pong!");
+///         message.channel_id.say("Pong!");
 ///     }
 /// });
 ///
diff --git a/src/ext/cache/mod.rs b/src/ext/cache/mod.rs
index 064add0..b39f5ea 100644
--- a/src/ext/cache/mod.rs
+++ b/src/ext/cache/mod.rs
@@ -368,7 +368,7 @@ impl Cache {
     /// let channel = match cache.get_guild_channel(message.channel_id) {
     ///     Some(channel) => channel,
     ///     None => {
-    ///         if let Err(why) = context.say("Could not find guild's channel data") {
+    ///         if let Err(why) = message.channel_id.say("Could not find guild's channel data") {
     ///             println!("Error sending message: {:?}", why);
     ///         }
     ///
@@ -414,14 +414,12 @@ impl Cache {
     /// ```rust,ignore
     /// use serenity::client::CACHE;
     ///
-    /// // assuming you are in a context
-    ///
     /// let cache = CACHE.read().unwrap();
     /// let member = {
     ///     let channel = match cache.get_guild_channel(message.channel_id) {
     ///         Some(channel) => channel,
     ///         None => {
-    ///             if let Err(why) = context.say("Error finding channel data") {
+    ///             if let Err(why) = message.channel_id.say("Error finding channel data") {
     ///                 println!("Error sending message: {:?}", why);
     ///             }
     ///         },
@@ -430,7 +428,7 @@ impl Cache {
     ///     match cache.get_member(channel.guild_id, message.author.id) {
     ///         Some(member) => member,
     ///         None => {
-    ///             if let Err(why) = context.say("Error finding member data") {
+    ///             if let Err(why) = message.channel_id.say("Error finding member data") {
     ///                 println!("Error sending message: {:?}", why);
     ///             }
     ///         },
@@ -439,7 +437,7 @@ impl Cache {
     ///
     /// let msg = format!("You have {} roles", member.roles.len());
     ///
-    /// if let Err(why) = context.say(&msg) {
+    /// if let Err(why) = message.channel_id.say(&msg) {
     ///     println!("Error sending message: {:?}", why);
     /// }
     /// ```
diff --git a/src/ext/framework/create_command.rs b/src/ext/framework/create_command.rs
index 357a597..68319af 100644
--- a/src/ext/framework/create_command.rs
+++ b/src/ext/framework/create_command.rs
@@ -54,8 +54,8 @@ impl CreateCommand {
     ///         .desc("Replies to a ping with a pong")
     ///         .exec(ping)));
     ///
-    /// fn ping(context: &mut Context, _message: &Message, _args: Vec<String>) -> Result<(), String> {
-    ///     let _ = context.say("Pong!");
+    /// fn ping(_context: &mut Context, message: &Message, _args: Vec<String>) -> Result<(), String> {
+    ///     let _ = message.channel_id.say("Pong!");
     ///
     ///     Ok(())
     /// }
diff --git a/src/ext/framework/mod.rs b/src/ext/framework/mod.rs
index 3c926a7..552ab93 100644
--- a/src/ext/framework/mod.rs
+++ b/src/ext/framework/mod.rs
@@ -43,12 +43,12 @@
 //!     .command("about", |c| c.exec_str("A simple test bot"))
 //!     .command("ping", |c| c.exec(ping)));
 //!
-//! command!(about(context) {
-//!     let _ = context.say("A simple test bot");
+//! command!(about(_context, message) {
+//!     let _ = message.channel_id.say("A simple test bot");
 //! });
 //!
-//! command!(ping(context) {
-//!     let _ = context.say("Pong!");
+//! command!(ping(_context, message) {
+//!     let _ = message.channel_id.say("Pong!");
 //! });
 //! ```
 //!
@@ -703,8 +703,8 @@ impl Framework {
     ///     .on("ping", ping)
     ///     .set_check("ping", owner_check));
     ///
-    /// command!(ping(context) {
-    ///     let _ = context.say("Pong!");
+    /// command!(ping(_context, message) {
+    ///     let _ = message.channel_id.say("Pong!");
     /// });
     ///
     /// fn owner_check(_context: &mut Context, message: &Message) -> bool {
diff --git a/src/model/channel.rs b/src/model/channel.rs
index 2c42405..1305472 100644
--- a/src/model/channel.rs
+++ b/src/model/channel.rs
@@ -58,13 +58,13 @@ impl Attachment {
     /// let token = env::var("DISCORD_TOKEN").expect("token in environment");
     /// let mut client = Client::login_bot(&token);
     ///
-    /// client.on_message(|context, message| {
+    /// client.on_message(|_, message| {
     ///     for attachment in message.attachments {
     ///         let content = match attachment.download() {
     ///             Ok(content) => content,
     ///             Err(why) => {
     ///                 println!("Error downloading attachment: {:?}", why);
-    ///                 let _ = context.say("Error downloading attachment");
+    ///                 let _ = message.channel_id.say("Error downloading attachment");
     ///
     ///                 return;
     ///             },
@@ -74,7 +74,7 @@ impl Attachment {
     ///             Ok(file) => file,
     ///             Err(why) => {
     ///                 println!("Error creating file: {:?}", why);
-    ///                 let _ = context.say("Error creating file");
+    ///                 let _ = message.channel_id.say("Error creating file");
     ///
     ///                 return;
     ///             },
@@ -86,7 +86,7 @@ impl Attachment {
     ///             return;
     ///         }
     ///
-    ///         let _ = context.say(&format!("Saved {:?}", attachment.filename));
+    ///         let _ = message.channel_id.say(&format!("Saved {:?}", attachment.filename));
     ///     }
     /// });
     ///
@@ -588,9 +588,9 @@ impl ChannelId {
     /// Change a voice channel's name and bitrate:
     ///
     /// ```rust,ignore
-    /// context.edit_channel(channel_id, |c| c
-    ///     .name("test")
-    ///     .bitrate(64000));
+    /// // assuming a `channel_id` has been bound
+    ///
+    /// channel_id.edit(|c| c.name("test").bitrate(64000));
     /// ```
     ///
     /// # Errors
diff --git a/src/model/guild.rs b/src/model/guild.rs
index 0ee68fd..03c5cfc 100644
--- a/src/model/guild.rs
+++ b/src/model/guild.rs
@@ -358,9 +358,9 @@ impl Guild {
     /// Create a role which can be mentioned, with the name 'test':
     ///
     /// ```rust,ignore
-    /// let role = context.create_role(guild_id, |r| r
-    ///     .hoist(true)
-    ///     .name("role"));
+    /// // assuming a `guild` has been bound
+    ///
+    /// let role = guild.create_role(|r| r.hoist(true).name("role"));
     /// ```
     ///
     /// # Errors
@@ -2446,7 +2446,9 @@ impl Role {
     /// Make a role hoisted:
     ///
     /// ```rust,ignore
-    /// context.edit_role(guild_id, role_id, |r| r.hoist(true));
+    /// // assuming a `guild` and `role_id` have been bound
+    //
+    /// guild.edit_role(role_id, |r| r.hoist(true));
     /// ```
     ///
     /// [`Role`]: struct.Role.html
diff --git a/src/utils/builder/create_invite.rs b/src/utils/builder/create_invite.rs
index 0f16b27..b3592d0 100644
--- a/src/utils/builder/create_invite.rs
+++ b/src/utils/builder/create_invite.rs
@@ -17,9 +17,9 @@ use std::default::Default;
 ///
 /// let mut client = Client::login_bot(&env::var("DISCORD_BOT_TOKEN").unwrap());
 ///
-/// client.on_message(|context, message| {
+/// client.on_message(|_, message| {
 ///     if message.content == "!invite" {
-///         let invite = context.create_invite(message.channel_id, |i| i
+///         let invite = message.channel_id.create_invite(|i| i
 ///             .max_age(3600)
 ///             .max_uses(10));
 ///     }
diff --git a/src/utils/builder/create_message.rs b/src/utils/builder/create_message.rs
index 5386c78..90a1f65 100644
--- a/src/utils/builder/create_message.rs
+++ b/src/utils/builder/create_message.rs
@@ -21,10 +21,9 @@ use super::CreateEmbed;
 /// Sending a message with a content of `"test"` and applying text-to-speech:
 ///
 /// ```rust,ignore
-/// // assuming you are in a context
-/// context.send_message(message.channel_id, |m|
-///     .content("test")
-///     .tts(true));
+/// // assuming a `channel_id` has been bound
+///
+/// channel_id.say(|m| m.content("test").tts(true));
 /// ```
 ///
 /// [`Context::say`]: ../../client/struct.Context.html#method.say
diff --git a/src/utils/builder/edit_profile.rs b/src/utils/builder/edit_profile.rs
index 4d25f00..83f1da2 100644
--- a/src/utils/builder/edit_profile.rs
+++ b/src/utils/builder/edit_profile.rs
@@ -22,7 +22,7 @@ impl EditProfile {
     /// ```rust,ignore
     /// use serenity::utils;
     ///
-    /// // assuming you are in a context
+    /// // assuming a `context` has been bound
     ///
     /// let base64 = utils::read_image("./my_image.jpg")
     ///     .expect("Failed to read image");
diff --git a/src/utils/builder/edit_role.rs b/src/utils/builder/edit_role.rs
index 3410417..e9b86e9 100644
--- a/src/utils/builder/edit_role.rs
+++ b/src/utils/builder/edit_role.rs
@@ -19,8 +19,8 @@ use ::model::{Permissions, Role, permissions};
 /// Create a hoisted, mentionable role named "a test role":
 ///
 /// ```rust,ignore
-/// // assuming you are in a `context` and a `guild_id` has been bound
-/// let role = context.create_role(guild_id, |r| r
+/// // assuming a `channel_id` and `guild_id` has been bound
+/// let role = channel_id.create_role(guild_id, |r| r
 ///     .hoist(true)
 ///     .mentionable(true)
 ///     .name("a test role"));
diff --git a/src/utils/builder/search.rs b/src/utils/builder/search.rs
index 6aaffca..904c580 100644
--- a/src/utils/builder/search.rs
+++ b/src/utils/builder/search.rs
@@ -90,9 +90,9 @@ impl SortingOrder {
 /// ascending order, and limiting to 5 results:
 ///
 /// ```rust,ignore
-/// // assuming you are in a context
+/// // assuming a `channel_id` has been bound
 ///
-/// let res = context.search_channel(message.channel_id, |s| s
+/// let res = channel_id.search(|s| s
 ///     .content("rust")
 ///     .has_embed(false)
 ///     .has_attachment(false)
@@ -124,7 +124,7 @@ impl SortingOrder {
 ///     let query = args.join(" ");
 ///
 ///     if query.is_empty() {
-///         let _ = context.say("You must provide a query");
+///         let _ = message.channel_id.say("You must provide a query");
 ///
 ///         return Ok(());
 ///     }
@@ -138,7 +138,7 @@ impl SortingOrder {
 ///         .map(|c| c.id)
 ///         .collect();
 ///
-///     let search = context.search_guild(guild.id, channel_ids, |s| s
+///     let search = guild.search(guild.id, channel_ids, |s| s
 ///         .content(&query)
 ///         .context_size(0)
 ///         .has_attachment(true)
@@ -152,13 +152,13 @@ impl SortingOrder {
 ///         Err(why) => {
 ///             println!("Error performing search '{}': {:?}", query, why);
 ///
-///             let _ = context.say("Error occurred while searching");
+///             let _ = message.channel_id.say("Error occurred while searching");
 ///
 ///             return Ok(());
 ///         },
 ///     };
 ///
-///     let _ = context.send_message(message.channel_id, |m| m
+///     let _ = message.channel_id.send_message(|m| m
 ///         .content(&format!("Found {} total results", messages.total))
 ///         .embed(|mut e| {
 ///             for (i, messages) in messages.results.iter_mut().enumerate() {