Calculate IsoFileContainerBox durations based on the length of the longest track (fix for CVP2RI-400)

 IsoFileContainerBox.get_duration() now iterates over all the tracks and
  returns the length of the longest one, instead of just the primary track.

 Some media files have a significant discrepancy between track lengths.
  e.g. The video track for B-AVC_MP4_MP_SD-01_2x.MP4 is 279 seconds
  while the audio track is 298 seconds. This causes a problem with the
  ODIDDataSource's scaled time-seek logic, which expects the 2.0- and
  -2.0-scaled version of a stream to be half as long as the normal-rate
  stream. This, in turn, causes the failure described in CVP2RI-400.

 Tested with a variety of MP4 files. But uncovered an existing/unrelated
  issue with O-AVC_MP4_HP_HD-01_-0.33x.MP4 - which seems to be degenerate.