Adding auto Twitch player selection

[RwbyChan]

I've made it so Twitch player will be selected automatically if available. I've tested this a couple of times over several days to improve it and it seems to be working for me, might need some extra testing by others as well!

I've kept the current URL overrides in case you want to keep those as well.

[LeagueOfPoro]

I am a bit wary of adding this style of Twitch player selection. It adds way too much complexity and the overrides work fine (most of the time).