Blocked a number of ways of getting out of the map. No more climbing the walls, guys.

Added numerous shotguns in Infection.
Added numerous DMRs in Slayer.

Added an extra man cannon leading to the top level.
Extended the pain field in the upper storey of the two-storey building to reduce teleporter camping.

Added more lighting effects around the starship wreck and the half-buried engine assembly.
Added a few more cover pieces in open areas.