Custom Map: Crossfire

Adds Half-Life's Crossfire deathmatch map as a PvP map. The map was remade from scratch using Hammer Editor as reference and imported into the game. It's not a 100% match to the original map, but I'm pretty sure it's close enough. Besides, I have added a few new additions.
MapLoader is required, otherwise nothing happens.

I have not really tested the map online because no friends to ask to, so it might not work. But hopefully it does right off the bat.

Credits to Bippuit for originally importing the map into the game. Also Zera for making the docs of setting up Unity, I guess. FireNoosta for making MapLoader and Valve for making Half-Life.