Fix for semi-transparent HUDs rendering opaque

and fixed diffuse alpha

This commit fixes a bug introduced with commit 6472b75b
where the fullbrightF.glsl shader fails to set color.a to final_alpha for HUDs.

SL-20611 Brute force fix for water haze -- paid for by cycles saved by not drawing water twice, but needs a better long term solution.

SL-20611 Followup -- fix for artifacts on water surface from GPUs that don't like to read from a depth buffer that is bound for writing

BUG-234706 Fix unstable performance on nvidia systems by always enabling Threaded Optimization via driver application profile (#564)

SL-20654 Fix for box probes sometimes glitching out at the corners.  Incidental fix for crash when mWaterPool is null.

SL-20611 Make haze effect local lights.  Incidental fix for EventPump coroutine sometimes doing unsafe work mid-render.

SL-20611 Followup -- fix edge cases with transparent PBR objects around eye/object above/below water.