Make parser.StateMachine build a list of operations in the reverse Polish notation

[DzyubSpirit]

The list should start empty and update after calls to StateMachine.move_one_step() as more tokens are consumed and the state changes from node to node.

The final list should be something like:

• For 3d4: ['d', 3, 4]
• For 4d2+2dice3: ['+', 'd', 4, 2, 'd', 2, 3]