MessageEmote: fixes emote replaced string with a hack until this can be re-written to something more sane, adds support for 7tv emotes

[swiftyspiffy]

Changes

• adds support for 7tv emotes (joins bttv and ffz)
• adds a hack that fixes the emote replaced string that's been broken for like 5 years
• this was originally referenced in ChatMessage.EmoteReplacedMessage should be populated based on ChatMessage.EmoteSet #21 . the codebase for this feature is actually... quite complex. this hack changes the generated regex match string to require either space on one side or both sides, which is effectively the rules Twitch uses

Emote replaced string test cases

• LUL DansGame "LUL"

https://static-cdn.jtvnw.net/emoticons/v1/425618/1.0 https://static-cdn.jtvnw.net/emoticons/v1/33/1.0 "LUL"

• LUL DansGame "LUL" LUL LUL "LUL" "DansGame" WutFace "WutFace" MrDestructoid MrDestructoid

https://static-cdn.jtvnw.net/emoticons/v1/425618/1.0 https://static-cdn.jtvnw.net/emoticons/v1/33/1.0 "LUL" https://static-cdn.jtvnw.net/emoticons/v1/425618/1.0 https://static-cdn.jtvnw.net/emoticons/v1/425618/1.0  "LUL" "DansGame" https://static-cdn.jtvnw.net/emoticons/v1/28087/1.0  "WutFace" https://static-cdn.jtvnw.net/emoticons/v1/28/1.0  https://static-cdn.jtvnw.net/emoticons/v1/28/1.0 

• LUL

https://static-cdn.jtvnw.net/emoticons/v1/425618/1.0