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.
* Resolve issue with copied v1 struct
* Speaking event patches, support Client Connect/Disconnect events
* Remove extra debug in heart.go
* Initial voice packet reading
* Resolve unallocated slices, use a static slice/array for decryption, split version/type
* Use separate slice for recvOpus, check return of secretbox.Open, and use constant for header size
* Update missing reference to packetHeaderSize
* Resolve decryption issues, add ReadPacket to session
* Update documentation for recvBuf/recvOpus
* Update comment for recvPacket's array
diamondburned
