Adds a mostly useless IOU vault.

Created by: gbasood

Adds a vault with a bunch of useless things in it. Some of those useless things are inside item mimics.

The entrance room up top is full of husk corpse spawners and some blood. The vault with invulnerable walls contains ONLY a broken case with an IOU note with a terrible cultural reference. There is an EMPTY russian revolver in a non-mimic crate. The mimic crates have vodka, cigarettes, happy pills and a trophy cup.

I wanted to add bloody footprints from the entrance to the gibroom but OH WELL

Feedback welcome. I'm not a mapper by any means.