* Added some functionality to PlaylistSearch to allow components to be
  saved and restored
* Added a member variable and accessor methods to Playlist to store the
  current search
* Cleaned up some of the code in Playlist to use PlaylistItemList instead
  of a QPtrList.

The next commit will actually make use of the above stuff to save and
restore searches when the user changes playlists.

svn path=/trunk/kdemultimedia/juk/; revision=229404