Reduced brightness of god rays across all maps

Fixed visual glitches with skyboxes

Changed lightmap scale on brush faces in main chamber to improve shadow quality

Improvements to lighting and sunshadows

Added toxic slime map

Fixed stepladder (was previously incorrectly using a prop_physics entity, when it should have been using prop_static)

- Sunshadows set to better angle, Light_environment set to values more suitable for this skybox. Should improve shadowing/lighting.

Fixed bugged lighting in largest hall

Minor lighting tweaks

Music will now play correctly if a save is loaded