following promotion of DRTVWR-596

More explicit cleanup in hopes of narrowing down which of the models
failed

SL-20611 Followup -- fix for depth based atmospheric mask making atmospherics effect sun/moon/clouds

following promotion of DRTVWR-587

in "new_folder_from_selected" at gInventory.getObject(*ids.begin());
according to bugsplat argument id was a null pointer so I assume there
was an issue geting id out of the list.

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)