* debian/control, debian/pictor.dirs, debian/pictor.postinst,
  index.php:
  - add video transcoding support to pictor
  - depend on libav-tools for avconv command
  - improve video embedding support by transcoding to h264 and use the
    html5 video element
* index.php:
  - extract the first image from a video and use it as a thumbnail
  - overlay a film strip icon on the video thumbnail
add support for mp4, use a "play" icon for video