Let everyone render in an offscreen buffer of 1280x720 pixels,
then blit to primary, scaling to target resolution.
This will need some calls to ->blit() sprinkled all over neutrino
which will come in a follow-up commit.
we're going to use the STFB blitter instead of manually
scaling everything if the videomode is not 720p, so more
or less revert all commits regarding FB scaling:
Revert "fontrenderer: scale fonts for nonstandard FB resolutions"
Revert "neutrino: resize framebuffer on videomode change"
Revert "fontrenderer: fix issue with epgwindow font when FB is scaling"
Revert "neutrino: fix artefacts with scaling framebuffer and 1080i"
Revert "spark: draw lines 2px wide instead of 1 in full-HD mode"
Revert "spark: do not scale framebuffer for PAL mode"
Revert "spark: fix framebuffer glitches"
Revert "spark: do not sync blitter after every rectangle (improves performance)"
Downscaling potentially looks bad and leads to ugly artifacts.
So for PAL mode, do not scale at all, just use the old-fashioned
big font look of dbox2 or tripledragon.
Only scale for modes bigger than 720p.
