incompatible changes to database and handling of incorrect track durations
- reset older database
- rename url(s) to file(s) in database and relevant code
- add cuefile to track entries
- accurate track lengths in database
- if track duration is estimated (it didn't come from a cue sheet) play
  the track to end of file, not to the estimated end of the track
- finish playing a cue sheet splitted track at accurate position