alpha:
-   highlight current song in playlist
-   support for more playlists

other TODO:
- don't quit by closing mainwindow?
- more advanced search in library
- queueing (MPD feature?)
- spectrum analyzer
- tagger
- split library by letters (like Amarok)
- icons could use a lot improving
- waste less memory (library and playlist are main suspects)
- Lyrics - should use only Qt's xml functions and allow user to select lyrics
- Get rid of the Settings widget. It's mostly useless -- its functionality
  should be moved to the plugins themselves
- switch to python3? -- waiting for PyQt4/PySide py3 support in Debian
- try PySide?