* Add BaseDiscordClient. Add various missing RequestOptions args.

DiscordSocketClient and DiscordShardedClient's shared members now exist in this abstract class.

* Add ShardReady event.

* Style consistency. Remove extraneous overloads.

Remove extraneous overloads.

* Add BaseSocketClient#DownloadUsersAsync().

Style cleanups.

* Add ShardLatencyUpdated event.

Style cleanup.

* Hook LatencyUpdated for ShardedClient.

* Begone whitespace.

* I'm good at this, I swear. >_>

* Add back DiscordShardedClient.UserPresenceUpdated

* Add ObsoleteAttribute

* Removing the UserPresenceUpdated event.