mp4chaps errs out if audio track is listed before video track

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Obtain an mp4 file with a video track but with an audio track as the first 
track.
2. Create a simple chapter text file.
3. Run mp4chaps to import the chapter file.

What is the expected output? What do you see instead?

I expect the chapter file to be imported.  Instead, mp4chaps errs out with 
"ERROR: unable to find a video track in file myfile.mp4 but chapter file 
contains frame timestamps"

What version of the product are you using? On what operating system?

Version 2.0 on Linux

Please provide any additional information below.

This problem comes from the ChapterUtility::actionImport call to 
ChapterUtility::getReferencingTrack.  The latter returns after finding the 
first video or audio track.  If the first one is an audio track, the 
isVideoTrack flag is left false even if a video track is present.

Original issue reported on code.google.com by co...@umn.edu on 24 Jul 2013 at 6:33