Build and install the NetHack.ad file, and change the nethack.sh to append
the HACKDIR to the XUSERFILESEARCHPATH. This means users do not have to
do anything special to use the NetHack X11 resources, nor does it require
teaching nethack where the X11 app-defaults directory is. The change also
updates the X11 and linux doc files in a corresponding way.
- Pat noticed that makedefs -z makes both vis_tab.[ch], but they could be
built by two makes via make -j, causing corruption
- make -j at top level failed for similar reasons, added several
dependencies to ensure a valid ordering
- these changes will cause extra things to be built if you "make"
individual targets at the top level, but have little effect it you're a
real power user and "make" the actual target in the right directory
