Feature: Allow setting scaling method

[Cybolic]

On a 21:9 monitor, a lot of background images get stretched so a way to indicate the scaling method used would be very appreciated.

Perhaps something like:
@time-time: [scaling] image1 .. [scaling] image2
where scaling can be one of the options supported by wallutils (stretch, fill, scale, tile, center)?

[xyproto]

Thanks for reporting! This should be added.