#7 Shrink state model with substates

[Dominik Breuer]

Shrinking states with substates improves the overview of the whole state machine. Therefore it should be possible to shrink a state with substates to a fixed size.
- trigger to shring or unshrink is a double click on the state model
- different header colour for shrunken states
- shrunken state should display shrunken substates/ display empty content (perhaps both cases are needed)
- state with substates should be displayed shrunken as default when machine states gets displayed
- relocate neighbour states if state gets shrunken or resized to the original size