Added the function of automatically switching wallpaper at regular intervals

[JohnLiao501]

This is a very powerful and conscientious software, I like it very much, and want to use it forever. However, the only drawback is that it does not have the function of automatically switching wallpaper at regular times, which makes me have to manually open the software and switch every time, which is very inconvenient. So we really hope that Mr. John can design a feature like this, so I would love to use it forever!