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;

2 files changed, 5 insertions, 3 deletions

diff --git a/examples/06_command_framework/src/main.rs b/examples/06_command_framework/src/main.rs
index 408fb9b..f4a3eea 100644
--- a/examples/06_command_framework/src/main.rs
+++ b/examples/06_command_framework/src/main.rs
@@ -14,7 +14,7 @@ extern crate typemap;
 
 use serenity::client::Context;
 use serenity::Client;
-use serenity::model::Message;
+use serenity::model::{Message, permissions};
 use std::collections::HashMap;
 use std::env;
 use std::fmt::Write;
@@ -88,7 +88,9 @@ fn main() {
         .command("commands", |c| c
             .check(owner_check)
             .exec(commands))
-        .command("emoji cat", |c| c.exec_str(":cat:"))
+        .command("emoji cat", |c| c
+            .exec_str(":cat:")
+            .required_permissions(permissions::SEND_MESSAGES))
         .command("emoji dog", |c| c.exec_str(":dog:"))
         .command("multiply", |c| c.exec(multiply))
         .command("ping", |c| c
diff --git a/examples/07_voice/src/main.rs b/examples/07_voice/src/main.rs
index 3870f9c..b1acc38 100644
--- a/examples/07_voice/src/main.rs
+++ b/examples/07_voice/src/main.rs
@@ -243,7 +243,7 @@ fn unmute(context: &Context, message: &Message, _args: Vec<String>) {
 }
 
 /// Checks that a message successfully sent; if not, then logs why to stdout.
-#[cfg(feature = "voice")]
+#[cfg(feature="voice")]
 fn check_msg(result: SerenityResult<Message>) {
     if let Err(why) = result {
         println!("Error sending message: {:?}", why);