Pyrevolt

- Added all remaining events (except ServerMemberUpdate) to session

- Corrected inefficient code
- Corrected bug with TextChannels which would not allow the bot to start

- Added the following events:
- MessageUpdate
- MessageDelete
- ChannelCreate
- ChannelUpdate
- ChannelDelete
- ChannelGroupJoin
- ChannelGroupLeave
- ChannelStartTyping
- ChannelStopTyping
- Added internal copy and update functions to user and channel objects

- Added bot commands and command error handling
- Updated typing from dict to list where appropriate
- Move to MIT license

- Added bulk gateway event handling
- Added mention property to user
- Added event dispatching from the Bot object
- Added bot and session GetChannel functions
- Added message Create and channel Send