Moves all half-pixel alignment to the screen view port function, this is
much more efficient sinec we only have to do it one time instead of
transforming every projection, it is also necessary to do it this way in
Direct3D 9 for repeating textures on surfaces. Also uses 0.25 in all
graphics systems since 0.5 only works with certain drivers well, 0.25
works best for all graphics systems and all graphics cards.