[git] Different Gravity Trap bug/exploit

[grmblfzzz]

I appreciate the prompt fixing of the no-dmg bug! This bug/exploit isn't localized to the git version, but seems it might be a handy time to address it. Anyway, the issue is this: Gravity Trap can be placed on 1-thick walls, and it'll effect stuff on the other side. Works through vault walls (doesn't dmg them in vault, but sucks them to the wall, then can kill them from outside once you open it though) as well as normal walls.

The easiest fix would be to disable being able to put traps on walls, probably... which if it's what you want c'est la vie, removing shenanigans is important. However, in my opinion a more targeted change at Gravity Trap such that if it's in a wall it doesn't do anything would be better. This is because other traps can be put into walls without being abusable (As they won't go off without lure, which can't be shoved through walls), and is extremely handy for lots of narrow corridors/corners, and for getting Wallwalkers as they come out.

[Hachem_Muche]

Another easy fix would be to just make vaulted NPC's Immovable as well as Invulnerable.

[grmblfzzz]

Well, that'd fix moving them around in vault... but the real problem is the damage through walls. Particularly because of how the trap works, in that it also sucks them in. You can really kill stuff 100% safely from behind any 1-thick wall. It's pretty abusable because you can always make circuitous tunnels leading to 1 square away from a room, then throw gravity trap on the wall and just kill everything there.