Fixed issue where recursive associations were not persisting correctly when the class was renamed. Added inheritancetree to the copy constructor. Fixed null pointer exception in parent validation. Altered UmlClassModel constructor and updated methods to use the passed in UmlClassModel (to the constructor) instead of relying on the textbox input.
Fixed issue with classes not being brought to the front when selected/dragged. Changed all occurances of rename class to modify class.
Fixed problem with bringing class objects to the front affecting inheritance lines
Added a few extra tests and fixed (I hope) the breaking test that I thought I had already fixed, where, when testing if the parent is already a child of the current class, because there might be no set parent pf the current class, then it was returning null instead
Fixed merge issues