Changed the handling of choosing ground/radius source files for constrained...

Changed the handling of choosing ground/radius source files for constrained and fixed points. Fixed seg fault when saving project containing footprint view containing a shape model. Update the control net name on the Footprint view when a new active control is chosen. Allow shape models without a footprint in the cube labels to be shown in the footprint view.  Fixes #5518, #5504, #5495.