NORSPEC-293 better fix incorporating srgb_to_linear curve and applying texture gamma corrections to spot inputs

NORSPEC-295 make a deferred path version of fullbright alpha mask shader so we can included gamma ops

NORSPEC-261 No more magic numbers, parity between forward and deferred rendering WRT to windlight and legacy shininess.

Reviewed by Graham (a little bit).

NORSPEC-238, NORSPEC-225 Fix for specular map alpha channel being improperly used and glossiness bludgeoning environment intensity.

Reviewed/written by Graham.

NORSPEC-229 Fix for bad binormals on mirrored surfaces (use tangent calculator instead of binormal calculator, convert binormal centric code to tangent centric)

NORSPEC-223 Fix for wrong textures displaying on fullbright+shiny faces with advanced lighting enabled.