v0.6.4

Fixed

• Timecodes pointing into an audio file are now clickable in the exported
  viewer. The citation pattern listed only video extensions, so an audio-only
  session — a recorder file with photographed slides, which this pipeline
  supports as a first-class source — rendered every (recording.mp3 03:23) as
  dead plain text. Nothing errored, because a non-match looks exactly like
  prose. On a two-day conference with four audio-only afternoon talks, 312 of
  536 timecodes were dead this way.