mod.io is a new platform for sharing mods, that 0 A.D. can make use of
in order to download mods and install them.
Based on patch by leper, numerous changes from s0600204, vladislavbelov,
Imarok, elexis, temple and myself.
Differential Revision: https://code.wildfiregames.com/D1029
This was SVN commit r21759.
