Workaround for building on GitHub's ubuntu-latest

Fix compilation on older gcc

Use BMP3 when generating win32 tiles

Wine has no problems with the default BMP format whereas a real Windows
complains and falls back to the default tiles.

Surround baalz-1 with lava

Also add the iron bars and the randomly mirrored secret doors from NetHack 3.6.

Release 5.2.0 info

NetHack 3.4.3

3.5.1