playlist subsystem overhaul

[Nikolaj Hald Nielsen]

> As a practical matter of landing the patch, there are some major
> crashes it currently introduces. I haven't looked into why. But we're
> on a pretty short schedule before beta3, so if its something
> fundamentally wrong with the new implementations we wouldn't have
> time. So I'd say either Soren should fix the crashes before committing
> or at least assure us thats its details that would be fixed in a day
> or two after committing  (this seems likely to me, btw, but I can't
> say for sure).

This is exactly the reason why I think we should get it committed as
soon as possible, as collectively, we can fix the crashes much faster
instead of Soren laboring away on this in isolation. I already have
one crash fix ready locally ( A simple missing sanity check )

- Nikolaj