Added classic game mode

Aligned some textures

added guns on ground for classic mode.

Added:
- A bottom to the pit.
- A lamp over the door.
- A radar image.
- Clip brushes (to help players not getting stuck).

Fixed / other:
- Bigger skybox so that the visable outsides of the outer walls are rendered and therefore cant be seen through.
- Added more func_details (lower stairs and rounded pitwalls) to hopefully lessen vis-blocks.
- Made extruding pipe parts non-solid and adjusted and added trigger_hurt blocks so now it shouldn't be possible to camp in the lower part of the pit... unless you have more than 500 or 1000 hp, depending on where you land >__>.