http://gtm.you1.cn/sharedfiles/filedetails/?id=807585816
http://www.moddb.com/games/alien-swarm/addons/forbidden-outpost
http://gamebanana.com/maps/193151

-minor balance changes
-minor visual changes (fog changes, less annoying special water, more accurate alpha on some diplacements, bad lighting one some model, etc)
-some perfomance optimisations and glitch fixes (ai pathfinding, bad collisions, vscripts api fountains precache and more)
-other minor stuff

Full source for developers included.