KDE Plasma is not supported

[evtn]

That's sad, but it appears there is no simple way

there is a script for that, but it won't work out of the box with splashpaper, because

Plasma does not update the image of the same file name when it is replaced

If anyone ever would need Plasma support (I'm unsure if feh fallback works there) and stumbles upon this issue, I'd be happy to accept a PR with alternating image names and ksetwallpaper integration