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-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-2465 Move FXAA to its own pass independent of DoF (also removes the need to reload shaders when toggling FSAA on and off)

SH-2465 Move FXAA to its own pass independent of DoF (also removes the need to reload shaders when toggling FSAA on and off)

SH-2507 Potential fix for basic shaders causing objects to disappear with some drivers (prune shader tree of unused shaders while we're at it)

SH-2507 Potential fix for basic shaders causing objects to disappear with some drivers (prune shader tree of unused shaders while we're at it)

SH-2507 Shave some unused/redundant varying state and make the max texture index debug setting rebuild shaders to use no flow control when set to 1 or lower

SH-2244 changes to run in a core context on AMD hardware without generating deprecation or performance warnings

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

SH-2242 Physics shape display works again, added asserts to flush out areas where state being consumed by a shader does not match state being provided by vertex buffers.

Reviewed by davep.

SH-2242 FXAA support instead of unreliable multisample textures (done here because it's a smaller change than integrating glVertexAttrib with FSAA pipe).  Shader integration with LLDynamicTexture subclasses.