Arena

A simple, dark arena-style map with plenty of weapons and ammo for deathmatch and team-deathmatch.

Changes:
-more ammo
-more shotguns
-more machine guns
-added a bfg
-less chainguns
-added four bunkers made with boxes in each corner of the map
-fixed wall bug (we could just see a black wall)
-deleted the hellknight
-fixed all the ammo and weapons to be just on the floor(not higher)