KFMI bug.  I removed some not-so-useful error checking and replaced it
with checking at more important times.

Also I made PlaylistItem::Data not a QFileInfo subclass since QFileInfo
doesn't have a virtual destructor.  I thought this might be the source
of the above crash, but I was wrong.  Anyway, this is a good thing...

svn path=/trunk/kdemultimedia/juk/; revision=216974