add linear/point screen filter option, add fill mode aspect 4:3 or 16:10 options

[rsn8887]

Added option to turn bilinear screen smoothing on or off
Fixed wrong aspect ratio in fill mode
Added choice of 4:3 or 16:10 aspect ratio in fill mode

[aagallag]

Nice work @rsn8887!

I see that the same PR was opened on MrNetrix's repo. In general, I have just been using this fork for my development work and hosting compiled releases, all of my changes have been getting merged to MrNetrix's repo. So my plan is to wait and see if MrNetrix merges the PR (or at least comments on it), in which case I will pull the changes from upstream. If no response from MrNetrix in the next few days, then I will revisit the PR.

[rsn8887]

Sounds good. I think if music can be added to this port it would be very nice. I know there’s a midi player included in Rinnegatanante’s Vita-Quake. It might work here, too...