Add a feature to let a PointSetInteractor be dependent on one data node.
Example situation:
Landmark Registration: Two different images, each shown in its own renderwindow (render specific properties), but both stored in the same data storage. Also added to data storage: two PointSets and PointSetInteractors each to be assosiated to one image.
Only the PointSetInteractor associated to the shown image shall add points to the PointSet.