Graphical improvements
General bug fixes

Fixed cubes not despawning when dropped into goo
Updated cubemaps
Moddified 3d skybox
Fixed geometry showing when it's not supposed to
Redid elevator base texturing
Made portal explosion sound quieter
Fixed fluorescent buzzing coming from the wrong location
Smokestack smoke is now thicker
Can collisions in the ratman den have been fixed (i.e. turned off)