Automatic title for playlists created from selection

[sonofevil]

I wrote this for personal convenience. Maybe it's gonna be deemed useful.

When a playlist is created from selection, the script will suggest a "ARTIST[ - ALBUM]" naming scheme, where ARTIST will be "Various artists" if there are multiple different artists, and [ - ALBUM] will be empty if there are multiple different albums. Basically the behavior of foo_playlist_manager.

Limitations:

• Only the first value of tags containing multiple values is taken into account.
• No customization.

Idk why the GitHub online editor automatically removed a few empty lines from the files.

[regorxxx]

Merged, edited afterwards with my own changes and code cleanup. Thanks :)