* Add operator[] to ConcurrentMap which returns a TValue reference
* BTTV/FFZ channel emotes are now stored in the Emote Manager, and each Channel object has a reference to their own BTTV/FFZ channel emote map.
* Restructure EmoteManager a bit (simplify the ConcurrentMap havoc).
* Add EmoteData struct which can store emote data (for now only messages::LazyLoadedImage*)
* Add CompletionManager that does nothing
