Redo game logic to use bitboards

[Bendi11]

Todo:

The game logic currently takes nearly 1000 lines of code just to barely operate. If the game logic could be totally redone to support bitboards instead of this crap, so long as it was done right, checking for movement legality could be as simple as AND-ing two numbers together. The majority of the Chess logic code is just repeated checks with functions providing move checks and stuff, so it hopefully shouldn't affect much else to change it all.

[Bendi11]

Game logic was only 456 lines long, and I couldn't see any way to improve with bitboards that wouldn't permanently cripple every other part of the game.