plparser: Add support for some GNOME XSPF extensions
plparser: Add support for some GNOME XSPF extensions

That should allow Totem to save all its metadata in the playlist
file rather than using side storage.

MathieuDuponchelle/totem-pl-parser,MathieuDuponchelle/totem-pl-parser,MathieuDuponchelle/totem-pl-parser,pwithnall/totem-pl-parser,MathieuDuponchelle/totem-pl-parser,pwithnall/totem-pl-parser