NetHackDS 3.6.7

Merge of upstream NetHack 3.6.7 release (plus a couple of extra commits after that).

A couple of key notes about this release:

1. NetHack 3.6.7 includes at least one major fix for builds on Linux environments, so older versions won't compile due to a gcc incompatibility when building 32-bit binaries on 64-bit systems (a necessity for this cross-compile to work).
2. I've also included, you know, all the Makefiles you need to actually compile this thing (though the build instructions still need some work, they don't currently mention the need for a 32-bit compiler environment, which is an important omission).