playlist subsystem overhaul

[Nikolaj Hald Nielsen]

> I'm known to put great emphasis on graphical perfection, and as such I
> have to say that the possibility of having proper animation in the
> playlist is absolutely crucial. It has been a design goal of the
> playlist from the beginning of Amarok 2 development. Even if we don't
> get animation done until 2.0 anyway, what use would it be to switch to
> a new system if we have to change it back later?
>
> So I would like to see proof for the feasibility of this before
> agreeing to switching.

To me at least, stuff like animation is completely secondary to having
a playlist that actually works. And Sorens patch, although it has a
ton of small and a few major issues, solves some very basic problems
with the old version, such as how to drag and drop multiple disjoint
items, dragging first track of an album seperately from the entire
album and several other corner cases.

This is why I am for committing it and letting us have a got at
getting the bugs out of it. Then we can evaluate whether we like it or
not.

As for feasibility, if the trolls can make animations work when
expanding nodes in a QTreeView, it should be possible ( although
likely non trivial ) to animate moves in the new playlist.

- Nikolaj