Add support for changing Nicknames!

User.Edit(nickname: "foo");

Added SelfBot Functionality by Config

Support Role Mentions

`Message.MentionedRoles` is now populated properly with roles.
`Role.IsMentionable` has been added to determine whether
`Role.Mention` now mentions roles that are `IsMentionable` as expected (otherwise returns empty string)
`Role.Edit` now takes parameter `bool? isMentionable`
`Server.CreateRole` now takes parameter `bool isMentionable`
`IsMentionable` added to `UpdateRoleRequest`

Add Nicknames to User Model; Bump README to 0.9.1

Add `User.IsBot` field, bump version number to 0.9.1

A few users requested an IsBot field for marking Bot Accounts;

Bumping Version number because it has been 0.9-rc3 forever and that's caused a bit of confusion in the channel with what version users are on.

Removed hack

check for server==null in User.ServerPermissions getter

Voice crashfix, Properly getting data for large servers.

Preliminary Unit-Testing

- Test User Mentions
- Test User Edit [UserUpdatedEventArgs]
- Test CurrentUser.Edit [UserUpdatedEventArgs]
- Test SetStatus 
- Test SetGame

- Test for Server.GetChannel
- Test for SendTyping [ChannelUserEventArgs]
- Test for EditChannel [ChannelUpdatedEventArgs]
- Test for Channel Mentions
- Test for DownloadMessages with/without cache
- Test for SendTTSMessage