Process list removal by making sure that we don't change the reference to the list
Fix problems with pasting keyframes.

In order to do this we also have to keep track of the limbs that are selected. When you copy/paste
a key, you must do it for every selected value. In order to do this our self.editing array also
needs to keep track of all of the limbs that are being selected as well.
Make sure that if we left click not on a key that we clear the editing array
Make sure self.drag is never None