Poltergeist postprocess overlap + optional damage fix 1.5r7 addon

poltergeist_detection_effector no longer stacks, limited to one at a time no matter how many poltergeists detected actor presence.

Also, if you find that damage they inflict with levitating trash is just too much - install damage fix.

Update 1: (Optional) lowered black poltergeist (Borovos) damage a bit as it is hard to hit only seeing minor particles movement