Subfolder for Playlist

[joesch2]

Feature Description

For a better overview of a larger number of playlists, it would be good to be able to organize playlists into subfolders. E.G. Subfolder "Standard" with Playlist DC-01, DC02, ..., Subfolder "Latein" with Playlist BAS-01, BAS-02, ... etc.

Thank you very much for this project!