Alpha 23 "lobby lag" release fix.
Caches the loaded mod versions, so that GetEngineInfo doesn't read the zip and json files everytime and returns about 1000 times faster.
Adds two missing includes.
The lobby froze multiple times every few seconds on updateGameList().
The gamesetup page was slowed down with every stanza sent and the
load savegame selection page was slowed down per savegame selection,
proportional to the number of installed zipped mods.