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.
This commit fixes race conditions in both package voice, package
voicegateway and package gateway.
Originally, several race conditions exist when both the user's and the
pacemaker's goroutines both want to do several things to the websocket
connection. For example, the user's goroutine could be writing, and the
pacemaker's goroutine could trigger a reconnection. This is racey.
This issue is partially fixed by removing the pacer loop from package
heart and combining the ticker into the event (pacemaker) loop itself.
Technically, a race condition could still be triggered with care, but
the API itself never guaranteed any of those. As events are handled
using an internal loop into a channel, a race condition will not be
triggered just by handling events and writing to the websocket.
diamondburned
