x11/xterm: document ncurses requirement (USES+=ncurses), plus ...
In addition to adding USES+= ncurses:
* specify libncurses instead of ancient libtermcap (which is symlinked
to libncurses anyway on FreeBSD base)
* Bring in USES+= alias from dports while here
approved by: infrastructure blanket
. Modify the nethack34 port to install itself in a versionsed fashion to
make way for a port of NetHack 3.6.0.
. Add a note to updating on how to preserve save and bones files.
Submitted by: firstname.lastname@example.org (partially)