[GSoC Update] Playdar Integration, Week 7

[Andy Coder]

This week was focused on getting PlaydarCollection/QueryMaker/etc. to
build.  I've got the build errors taken care of, but PlaydarCollection
needs some retooling.

The trouble is, Meta::PlaydarTrack's setters want Playdar*Ptrs, (and
this works great for the most part, since we can ::staticCast() to
*Ptrs), but MemoryCollection wants to store everything as *Ptrs.  This
becomes a problem when we're adding tracks to the collection, since I
try to use Albums/Artists/etc. that are already in the collection
before new ones, (but these can't be set directly in PlaydarTrack).
If there's a good way to downcast the Meta::*Ptrs to
Meta::Playdar*Ptrs, (which should be safe, since anything that's
supposed to be in the collection should've been created that way), I
could use that.  Otherwise, I've got to either implement a
PlaydarCollection-specific storage scheme or decide that duplicate
objects other than the tracks themselves aren't worth worrying about
for now, (I suppose I could at least try not bothering and see how it
goes for the sake of having something build and run).

 - Andy Coder