Terrain code should not use its own GL error function when we have a better one elsewhere.
Performance measurement hotkey added. Press ctrl+k in debug mode to grab a sample.
On level exit, it writes a .csv file with your samples. Also, for each sample it
writes a screenshot with a custom filename, so you can match up the sample with a
picture of what you sampled. For analysing where we have graphics performance problems.
Add back alpha test for non-pre-multiplied mode PIE models for now.
This closes ticket:4071
Misc display3d cleanups