LOW/ Update TA-38: Freeplane support
https://bugs.openflexo.org/browse/TA-38

Improve ergonomy on add. Still problems on remove.
Add Flexo Roles for node and Map in model slot. Implementation may not
be complete, use at your own risks. (Specific actor references not
defined)

TODO: (Unsorted)
	- Some clean up on action available in right click
	- Flexoroles ?
	- Update model on addNode Actions.