Implement classical moves and rule checks

[madcpf]

In Board:

• add path_pieces() to return the classical and quantum pieces in the path;
• add flying_general_check() to check if two KINGs meet directly.

In Chess:

• add check_classical_rule() to check if the move is classically allowed;
• add classify_move() to classify moves into MoveTypes and MoveVariants;
• update apply_move() to apply the classical moves.

In Enums:

• update MoveType to remove the redundant move types.

In Piece:

• add reset() to set the classical attributes of the piece.