Merge from vendor branch TNF:

Merge from vendor branch TNF:
Import z26 from pkgsrc-wip.  Packaged by Greg Troutman.

A fast and stable emulator for the mighty Atari 2600 game console.
Lots of features and options, even comes with a man page with gobs of
detailed information to help you fine tune everything.  Try the
various timing and video mode settings to get the maximum performance
on your computer.