x11-wm/rubygem-uh-wm: create port

uhwm is a minimalistic tiling and stacking window manager for X. It shares some
similarities with dwm and wmii, but is written in ruby so you can configure and
extend features directly with ruby code.

WWW: https://rubygems.org/gems/uh-wm

PR: 216434
Submitted by: Thibault Jouan <tj+freebsd_bugs@a13.fr>