Toggle to crop character sprites to background instead of viewport

[Samevi]

Characters currently do not crop to background and instead are fully reliant on the viewport size. This means that for themes with a widescreen viewport, using 4:3 aspect ratio backgrounds without stretching to viewport results in characters wider than the background clipping into the blank space outside of the background. See image for demonstrated result.

There should be a toggle in settings to change this behavior so that characters instead crop to content and do not extend beyond the background boundaries. See image for expected behavior.

Screenshot and idea originally from andrystein03