Add new port graphics/nomacs:
nomacs is small, fast and able to handle the most common image
formats. Additionally it is possible to synchronize multiple
viewers. A synchronization of viewers running on the same computer
or via LAN is possible. It allows to compare images and spot the
differences (e.g. schemes of architects to show the progress).
PR: based on ports/170666
Submitted by: Jens K. Loewe <bsd at tuxproject.de>