DRTVWR-559 Quality pass -- Fix sky banding, fix off-by-one-mip in reflection probes (thanks Rye), remove noiseMap from light shaders (removes speckles), make irradiance maps RGB16F instead of RGBA16.  Use actual luminance for sky instead of max color component during irradiance map pass.

SL-19147 Water quality pass.  Remove gl_FragDepth writes from sky rendering (optimization).  Incidental decruft.

SL-18190 Cleanup -- convert some vec4's to vec3's (as they really are), remove some unused glsl files.

SL-14113: Remove magic numbers. Take advantage of existing shader #defines injection by extending shader loading to make use of addConstant() instead of hard-coding magic number constants in each GLSL file.

SL-14113: Remove magic numbers. Take advantage of existing shader #defines injection by extending shader loading to make use of addConstant() instead of hard-coding magic number constants in each GLSL file.

Remove all references to unused shader var global_gamma.

Remove many unused decls for gamma from shaders.

Make post-deferred gamma correction use display_gamma.

Make setting display_gamma use the correct RenderDeferredDisplayGamma setting.

Make fullbright rigged objects with alpha mode none use fullbright shader instead of incorrectly using the material shader.

Increase effect of variance in cloud shaders.

Fix culling on Low+ water reflection pass.

Make Mid+ / High use class1 deferred sky again (no rainbows, but faster!).

Fix setting of cloud color for deferred sky/cloud shaders.

Put water reflections back in wrong colorspace for consistency with release.

Gave clouds the Bob Ross treatment.

Make alpha shader apply vert color everywhere.

Fix direct light matching across alpha/blended-material/deferred.

Get diffuse lighting to match from Low to Ultra.

Apply sRGB colorspace to deferred cloud output.

Fix skydome VB generation to cover entire range of phi (give sky pants).

Add shader code to fade out clouds to simulate old look at altitude.

SL-9851

Fix cloud shaders to ignore clouds when cloud_scale is 0.

Fix creation of heavenly body geo to avoid degenerate vector math
and not randomly flip orientation when crossing zenith.

Add sun_up_factor to eliminate sun glow around moon when sun is down.

add cloud_variance control for randomized perturbance of clouds to break up tiling monotony

Make sky and cloud shaders use common scaleSoftClip implementation in gammaF.glsl

Make cloud rendering use textures defined in sky settings and add code to shaders to lerp between current and next cloud texture.

Fix warnings from shaders and include EXTRA_CODE_HERE sentinel in places using DEFINE_GL_FRAGCOLOR for consistency.

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-2243 work in progress -- don't use gl_FragColor or gl_FragData for outputs -- no more deprecation warnings on nvidia

SH-1682 Dynamically adjust the number of texture channels to use for indexed texture rendering based on available hardware.