Minor vault batch

Mostly decorative vaults, except for one horrible monster pairing
that I've had at the back of my mind occasionally for ages.
Also, some nearby .des clean-up, with header standards imposition
or some organization stuff or whatever.

I briefly wanted the Lair and Zot vaults to have serial-vault-like
placement to repeat the weird shapes on a floor, but there are a
bunch of ugly implementation problems or letting them spill across
more than one floor each. It'd be mildly neat for some rather simple
decorative vaults to be capable of such a trick through vault.lua
and some recursive dgn.place_maps or whatever, but this seems rather
excessive for these cases for now, so whatever.