Fixed: crash of the CPOutlineView when reloading and changing an item to another parent

Previously, when reloading the CPOutlineView and changing an item to another parentItem, the CPOutlineView deleted the reference of the item.

Now, when removing old data to avoid memory leaks, the CPOutlineView checks if the pending item to delete doesn't have another parent item.
Merge pull request #2178 from Dogild/CPOUtlineView-fix-reuseItem

Fixed: crash of the CPOutlineView when reloading and changing an item to another parent