[Playlist] [rfc] Nested playlists (and playlist chains) again

[Lucas Gonze]

On Fri, 12 Oct 2007, Rafaël Carré wrote:
> We use that format for the "Media Library", i.e. a playlist that will be
> loaded at each startup, so that's meant to last forever, untill items
> are deleted from the playlist manually.
>
> You can add a directory to VLC's playlist and see the nested structure
>
> Dir
> 	Subdir1
> 		File1_1
> 		File1_2
> 	Subdir2
> 		File2_1


Ok, so how do we characterize this functionality in more general terms? 
We need to turn this into abstractions.

I think that the point of this is navigation.  It enables users to 
navigate playlists as collapsable outlines, so they can skip over or 
descend into sets.