Feature gl stereo option
Added Setting and commandline option to request Stereo Buffers on OpenGL context creation. closes https://www.graphics.rwth-aachen.de:9000/OpenFlipper-Free/OpenFlipper/issues/17
Added Setting and commandline option to request Stereo Buffers on OpenGL context creation. closes https://www.graphics.rwth-aachen.de:9000/OpenFlipper-Free/OpenFlipper/issues/17