Common resize options

[anufrievroman]

Hi, I am a maintainer of waypaper app, that uses swww as one of the backends for wallpaper setting. I have one suggestion:

Classically, wallpaper fill modes are either fill, fit, center, stretch, or tile, which are all different things. However, swww --resize only supports no, crop, and fit. So, I guess no is center and crop is fill, but stretch and tile are not present. I'd suggest implementing these modes as well, just to be more uniform with other wallpaper tools. Thank you.

[Visual-Dawg]

Also adding the option for no resize to scale images to the screen size if they are larger than the screen, but otherwise leave them as is, would be really nice :)