Enable offscreen hardware accelerated rendering on server
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
Right now, the --UseOffscreenRendering flag only has an effect if compiling with OSMesa.
Our servers have nodes with more CPUs than GPUs. We want to try launching a job with one process per CPU and have them share GPUs. However, if they both pop up a window on the screen, then the image buffers clobber each other. We should be able to get around this by enabling hardware-accelerated offscreen rendering.