pyrogenesis can now take a zip file (rename it to .pyromod for direct
file association following 943a61e4ea) and install it. It then starts
the mod selector.
Patch by vladislavbelov, with contributions from Imarok, elexis and
myself.
Differential Revision: https://code.wildfiregames.com/D1142
This was SVN commit r21726.
