This commit consists of these smaller commits:
Gateway: SessionID to be a method for thread safety
This commit breaks the SessionID field of the Gateway struct to
be thread-safe by wrapping its access with a read-write mutex.
As this is a bug fix, it is reasonable of a breaking change
Heart: Allow later binding of event channel
Voice: Use the new Heart API
Heart: Fixed data races
Heart: Allow changing pace, thread-safe Heartbeat
This commit gets rid of all the code that previously managed different
voice sessions in different guilds. This is because there is rarely ever
a need for this, and most bots that need this could do their own
keeping.
This change, although removes some features off of the package, adds a
lot of clarity on what to do exactly when it comes to connecting to a
voice channel.
In order to make the migration process a bit easier, an example has been
added which guides through using the voice.Session API.
