Integrate Themes via Menu Bar

[PatrickBruso]

Custom Tkinter is a python UI-library based on Tkinter, which provides new, modern and fully customizable widgets. We need to update our application to use custom tkinter so that our application has a more modern feel.

[PatrickBruso]

I am going to attempt to integrate some themes, probably using the sv_ttk library, by adding a menubar item. I will then let the user decide between a "light" theme and a "dark" theme.