[FEATURE] Access to Parent Source State on entry of SubState

[erikzenker]

Problem
The on_entry action of a state does not get the parent source state as a parameter. But the parent source state could be handy when you need to access its data members e.g. to start a timeout.

Current Workaround
Instead of storing data in the parent source state you can add additional members to the dependency struct.

Proposed Solution

Provide the parent source state to the on_entry function. The same holds true for the parent target state for the on_exit function.