Add option to copy wallpaper to a file instead of setting the wallpaper

[Kagia001]

That way we can use other pywal arguments, use pywal alternatives like lule, use a different wallpaper setter, or do whatever else you may want to do with the wallpaper. It makes more sense to atleast have the option to not set the wallpaper, the script is a lot more flexible like this.

[ghost]

Hi @Kagia001, it appears that @adi1090x has abandoned this project (the last commit was in January), but I have continued development in my fork Dynamic Wallpaper Improved. Feel free to open your PR there so I can merge it! 🎉

[erwinwallpaper]

Nice suggestion

[adi1090x]

Sorry for being way too late.

Nice PR, can you resolve conflicts and reproduce it?