Revert previous change because breakpad's ExceptionHandler class has different API on diff platforms

NORSPEC-57, NORSPEC-58  Remove sRGB and gamma correction from shaders to remove banding and not break all shiny objects.

I don't know what added this requirement, but this last night lots of
them started failing to link.
Also remove some obsolete commented-out stuff

Added "Selected Material Info" menu option to query basic material information about the current selection

Prevent a failed GET from causing an infinite material request loop when there are still pending POST requests for the same region