discid: also display track durations in minutes and seconds

Example:
```
Length        : 356163 sectors ( 1:19:08.84)
Track 1       :      150    33284 ( 7:23.79)
Track 2       :    33434    43480 ( 9:39.73)
Track 3       :    76914    13717 ( 3:02.89)
Track 4       :    90631    52078 (11:34.37)
Track 5       :   142709    24078 ( 5:21.04)
Track 6       :   166787    33604 ( 7:28.05)
Track 7       :   200391    23830 ( 5:17.73)
Track 8       :   224221    46629 (10:21.72)
Track 9       :   270850    73423 (16:18.97)
Track 10      :   344273    11890 ( 2:38.53)
```