This is a port of Jigsaw Download (AKA jigdo) which is a tool designed to
ease the distribution of very large files over the Internet, for example
CD or DVD images.

Main features:
    - The large images does not need to be stored on the server, instead only
      the small files contained in the images (works with CD, DVD images,
      uncompressed zip files, tar archives...)
    - In spite of the above, jigdo creates a bit-exact copy of the image on the
      user's machine (to achieve this, the directory data, boot block, etc. of
      the image is stored in a special .template file which is distributes
      alongside the .jigdo file)
    - There is full control over where jigdo-lite will download the individual
      parts. It is possible to define mirrors, so users can choose the nearest
      one.
    - jigdo relies on standard HTTP/FTP, no special protocols needed.
    - jigdo-lite supports resuming aborted downloads, or continuing the
      download with another mirror if the current one is slow.
    - It is possible to "upgrade" the CD image, only the changed data will be
      downloaded.