current_type - string representing the current piece's type; "unknown" for a superposition
Board - Class to represent a quantum chess board. InternalAgent.board is one of these.
+ pieces[] - Dictionary that maps a colour string ("white" or "black") to a list of Piece's
+ - ie: Use to get your pieces
possible_moves(self, piece, state = None) - Return a list of possible moves for piece.
- If state is None, the piece must be in a known classical state
- If state is not None, the state of the piece will be temporarily set