Keep the pixel-art scaled frame upright on OpenGL
FixedPlanned for 0.2.0
On OpenGL, the default pixel-art filter showed the picture upside down whenever it enlarged the frame by a factor that is not a whole number, as it usually does in fullscreen. The picture is now upright. Other renderers, the other filters, and whole-number enlargements already showed it upright and are unchanged.
Credit: EJ