VAM Plugin: Remove Atoms from Selection

As per user request, this is a convenience plugin that adds an X-button in the Atom Selection menu to remove single Atoms from the Scene.

Please note: when you want to remove a large subscene, it can cause VaM to hang. It might be a good idea to clear out subscenes before removing them, as VaM has to do a lot of work under-the-hood when removing atoms.

Update v1.1:
- as per user request, there is now an additional button to turn an Atom on or off. The color of the light bulb icon (green/black) also indicates, whether the Atom is enabled or not: