Clean up some shaders. Fix skybox.

Skybox was disabled, but this reenables it.  It seemed slightly off before, this is better.  Not perfect, but better.
Fix some comments in other shaders.
Improve d3dx.ini settings for SR3.

Set SurfaceCreateMode=1, in case people use Low lighting.
Set default profile in case they use null profile for Low lighting.
Set scissor to disabled, to avoid lights clipping.
Add HUD shaders for SR3.

These are based on Mike's approach, but when it's enabled, it causes weird side effects like broken eybrows, tattoos, lights going red/blue.
I think I'll leave it at zero, but other people may want to push them to depth.