Accept NOT operator for State Machine members

[VigneshVSV]

Currently, if an action or property write has to executed in all states except one, it must be specified for all those states. However, it would be better to specify it with NOT operator on the specific state where it must not be allowed.

state_machine = StateMachine(
        states=states,
        state1=[...], # ... means other actions and properties
        state2=[...,  not prop1],
        state3=[..., not action1],
        state4=[...]
    )

This should translate to not allowing action1 in state3, but allowing it in all other states.

Possible steps include

• come up with a scheme how to carry over this metadata to the StateMachine object, it will mostly involve overriding the __bool__ operator
• factor in logic in set_state() method