Feature request: non square pixels or aspect ratio independent of width/height

[Fieoner]

I run itgmania on a CRT at 3840x780 with a 4:3 aspect ratio
deadsync calculates the ratio based on the resolution so I have to set it to 1040x780 to be able to have it display correctly on that CRT.
It would be cool to support this itgmania feature here.