Include QtGui instead of glu.h (more exhaustive openGL definitions)

QtGui provides GL_BGR and GL_BGRA on Windows, whereas the default Windows
OpenGL header does not. Before this commit, the image test in AutoTest
was failing because of inverted blue and red colors on Windows.

QtGui also provides GL_YCBCR_422_APPLE and GL_UNSIGNED_SHORT_8_8_APPLE
even on Windows, so hardcoding their values is not longer needed.
Merge pull request #210 from tlecomte/tlWindowsBGR

Include QtGui for OpenGL headers