Abstractions should reduce the amount of code and make things
easier to follow.  The StoredPlaylist struct did not do that, so
get rid of it and just use our standard linked list
implementation instead.

diffstat agrees with me that the abstraction is pointless:
3 files changed, 60 insertions(+), 90 deletions(-)

git-svn-id: https://svn.musicpd.org/mpd/trunk@7120 09075e82-0dd4-0310-85a5-a0d7c8717e4f