Use startEditing/endEditing as method names for controller enabling/disabling, require explicit calls of insertlocalcursor/removelocalcursor

Fixup to Restore SessionController.startEditing/endEditing inserting/adding the local cursor
Rather take the current parentnode of eventtrap to remove from tree

Fixup for Add gui.EventManager.destroy
Fix InputMethodEditor.destroy not unsubscribing from all events