The module PlanarFigure shall be extended to allow adding and deletion of control points in ROIs (PlanarPolygon). The follwoing changes should be implemented:
1.) The state machine implemented in the class PlanarFigureInteractor needs to be extended with new states and transitions to allow adding and removing of control points in general, as described above (including the "hovering" effect of marker points when the mouse is over an existing edge of a polygon)
2.) The PlanarFigure module needs to ensure that removal and adding of control points only works for specific PlanarFigure objects. Several possibilities exist; one might be to add a parameter to PlanarFigure objects which allows / disallows adding / removing of control points. Also, a mechanism needs to be implemented to communicate the position of a marker point for adding control points.
3.) The class PlanarFigureMapper2D (responsible for drawing PlanarFigures) needs to be extended with the possibility to draw "marker points" when the mouse is over an existing edge of a polygon (on which control points can be added)