Part of "improve filtering situation" (#116980), now strip scaling
filter defaults to "Auto" which has logic like:
- No scale, no rotation, integer positions: Nearest (fastest)
- Scaling up by more than 2x: Cubic Mitchell, so you get nicer
blending between pixels than with bilinear,
- Scaling down by more than 2x: Box, so that many pixels are averaged
properly without too much aliasing,
- Otherwise: Bilinear
Existing strips that use Bilinear (which is default) get switched
to Auto when loading older files.
Aras Pranckevicius