[MWR] Gungrouping

OK, here's the initial rework of gun distribution.  Basic ideas were that police typically will have fairly standard gear in their armories, civilian stashes probably won't have automatic/military weapons (or at least not top-of-the-line ones), and survivalists will bias toward weapons suitable for hunting rather than combat.

On the bright side, LMOE guns come loaded now and Rivtech gear should be a bit more common.

I've got it about where I want it, I think.  Merge when ready, please.