gr_fakecontrast and gr_spritebillboarding in the OpenGL settings menu
requested to merge sonic_edge/SRB2:grfakecontrast-and-grspritebillboarding-in-opengl-options into next
This MR resolves #406, allowing the console variables gr_fakecontrast and gr_spritebillboarding to be accessible from the OpenGL settings menu, just like in SRB2Kart. As far as I'm aware, there's no reason to keep it out of OGL settings in vanilla but if there's something the matter I can close this.