Change the general appearance, dock and menu bar setting to be dark or light independently

[RamonGilabert]

Instead of making users run a command in the terminal, we could make the same inside the app, as it's related and would love to use that myself.

For reference: https://www.tekrevue.com/tip/only-dark-menu-bar-dock-mojave

[zenangst]

Looks like dock and menu bar is coupled so we might not be able to change them independently

[RamonGilabert]

I think that works, too, I'll create icons for both cases, just in case (: