Convert EDL file (like Channels DVR emits) to a file suitable to be used
with the --chapters option provided by mkvmerge
The file created is a full XML-style chapters file, containing chapters for both the show content and for the commercial breaks. This makes it easier to load up the mkv file into a video editor later to remove the commercial breaks.
Note: Some editors (e.g. VideoRedo) only import the 'start' timestamp of each chapter as a 'chapter mark'.