Plus some code deduplication

Blitting or resolving multisampled images requires the dimensions of the src and dst to be equal for valid usage, making them difficult for resolution scaling using the current implementation.

Fixes screenshots at non integer scaling

We don't need to reconstruct new textures every time we ScaleUp/ScaleDown. We can scale up once, and revert to the original texture whenever scaling down.
Fixes memory leaks due to glDeleteTextures being deferred for later handling on some drivers

Fixes scaling in Super Mario Party

Thanks for everything!