playlist support during collection scans.
amarok will now load found playlists during a scan.

however, still have not implemented duplicate checking - so if you rescan, they will show up again.
also, removed the reload-db call every time a playlist was added, because it seemed to stress some part of the playlistbrowser or db code and would make amarok crash.

you might need to jiggle amarok a little to get it to show them right after a collection scan is finished.