Fix rendering when not upscaling chroma, and make it default

[spillerrec]

Upscaling chroma when rendering is quite slow and uses quite a bit of memory, so we should avoid this and make this the default operation.
This was tried but dropped earlier, because there were minor alignment issues. But thinking about it, it actually makes sense because it actually does sub-pixel rendering. We should let that to the actual sub-pixel or hopefully soon, SR renders.
It also seems broken currently, so fix it...