Vlad's tower has Vampires in 'coffins'

+4 containers are now considered coffins, and have vampires in them. When the container is opened for looting or destroyed by a lockpick attempt, the vampire gets out.

Also fixes a bug where, if the box with Schrodenger's cat in it is destroyed, no cat is created.
Merge branch 'master' of https://github.com/Chris-plus-alphanumericgibberish/dnethack.git