[GREENFOOT-41] Move classes in the class browser
It would be nice to be able to move classes in the classbrowser. This can be divided into two cases:
- Moving just for the sake of rearranging the order in which the classes are displayed
- Moving a class to another hierachy \- giving it a new super class.
Changing the super class is now supported. Changing the super class in the editor will be reflected in the class browser
- Issue type: Task
- Priority: Medium
- Fix versions: 3.0.0