impliments board::in_check?
implements check_mate?
implements chess
fixes bug where piece::available_moves was returning nil
removes recursive loop in board::in_check?
implements pawn attacking moves, also allows pawn to move two spaces
fixes bugs w/Rook and Bishop movement
separates each piece to its own file
separates each piece to its own file
So. many. problems...
So. many. problems...2