[Feature request] Name playlists according to the Spotify playlist they came from, instead of _playlist.m3u8

[MXC1]

This would allow users to automatically import the .m3u8 files into a music library, like MusicBee, iTunes or Rekordbox.
I imagine this would be a simple change.

[fiso64]

This is a default because it makes it easier to find the m3u file among the downloads as it will be the first file.

I'll add a variable {playlist-name} for --playlist-path to make it work as you say. The path will be relative to the output folder, so setting playlist-path={playlist-name} will put it in the same place as before but using the name of the playlist instead of _playlist.