Added craft

Craft - A simple Minecraft clone written in C using modern OpenGL
(shaders)

http://www.michaelfogleman.com/craft/

Note that there are no stable releases of Craft on GitHub in the form of source code, but stable release binaries are available from the website, which deems this source code as stable (enough), but perhaps `headonly` is a better home? I figured that people would search for it as a game before they searched for it as a head-only formula.