Hopefully fixed all missing textures and other errors.
Feel free to comment with screenshots if anymore missing textures are found.

Finally cleaned up the map thoroughly.

Fixed up a few more unsightly aspects.
Removed a Combine spawn where it shouldn't be.

Removed glitchy entities, moved Combine spawn further NE, and
adjusted terrain at Combine base to swallow up part of it.

Fixed lighting and garage walls at Rebel base.

Hopefully fixed missing texture

Added AI nodes.