Support newest version of MiSTer

With the new updates to the Linux system on MiSTer there is a new and improved method of running tasks during startup. Which is called the upser-startup script. This update changes to use this system instead.

Random Wallpapers

New functionality! Added preliminary support for MiSTer's random wallpaper, see the readme for more info. as requested by u/ENzeRNER on reddit

If you are upgrading, if the script had a different name then please remove it or uninstall the old version first.

This binary includes rewritten bugfixes and functionality which was in the binary release but I had lost the source code for. Should be very comparable in how it works, but written differently.

First release

Add the binary to your scripts folder and rename your wallpaper from menu.png to wallpaper.png
Then run this script and say yes to installing it as a service.