Selectable lyrics import

Example of karaoke file with one lyric track:
https://docs.google.com/file/d/0B5alKuFoSol2SlI4VGU2X0IzQ0k/edit?usp=sharing

These "comboboxes" gives an opportunity to select the track to assign lyric to.
Multiple lyric tracks are also supported (but not tested yet - no suitable .kar file).