SH-2908 Rework indexed texture rendering to use a uvec4 instead of a float for texture indices in the data stream.  Also rework gl_FragColor overrides to not collide with some odd driver implementations.

SH-2592 FIX -- (OS X Lion) Graphics issues with Atmospheric Shaders enabled on Intel HD 3000, 10.7.2

This is a dummy check-in to get the previous commit associated with SH-2592 instead of EXP-2592, which was a typo.

EXP-2592 FIX -- (OS X Lion) Graphics issues with Atmospheric Shaders enabled on Intel HD 3000, 10.7.2

* Fixed up shaders to add haze_density and blue_density together correctly as vec4's rather than
  relying on the shader compiler to add them together properly.

SH-2592 PROGRESS -- (OS X Lion) Graphics issues with Atmospheric Shaders enabled on Intel HD 3000, 10.7.2

Refactored WindLight estate settings to use float uniforms in the shaders that
only need it, rather than vec4's for everything.

* Cleaned up vertex buffer allocation to guarantee allocation and deallocation using the same allocation methods from the same pools.
* Added new shader feature for atmospheric helpers in the absence of lighting.

Reviewed by davep.

SH-1427 Fix for spot lights not working properly on alpha objects, and fix for alpha lighting of point lights not matching deferred lights.

Removed unused code from alpha fragment shaders to fix some mac rendering glitches with non-fullbright alpha objects.

SH-1619 FIX
SH-1620 FIX
SH-2621 FIX

* Got lighting, shadows, and ambient occlusion working on ATI macs.
* Re-enabled ambient occlusion on ATI macs.
* Re-enabled depth of field on ATI macs.

Reviewed by Runitai Linden.

SH-2652 Slightly slower DoF (quality), apply FXAA *after* DoF, fix for some render targets not getting allocated when needed.

SH-2541 Fix for speckles on avatar on some cards -- don't use "maximum_alpha" for alpha tests in shaders as it was always being set to 1.0 anyway.

SH-2546 Fix for black avatars and terrain on GF Go 7800 (use vec3 instead of float on varying parameters).

SH-2031 Fix for stall in image update -- don't use the CPU to convert a height map into a normal map -- use the GPU instead via a shader.  Also, WTF glFinish?

SH-2447, SH-2525, SH-2276 Strip out defunct global illumination code, add accounting for how much memory is taken up by LLRenderTarget, fix crash on login in bindGLIndices (work around driver bug that doesn't respect VAO state WRT to index buffers), remove some unused render targets, remove some unused shaders, make it possible to run a fullscreen session