- Have another look at calculating focal_factor for Fuji cameras.

- Decode more Canon-specific data.

- When ingest prunes everything on a card, mdir reports an error when the
  card is empty.  Not a serious problem, but would be nice to clean up.

- My current installation of ImageMagick fails on gzipped images.
  Track this down.

- Allow repeated images in config/setup.

- Optionally use The GIMP to manipulate images instead of ImageMagick.
  This will allow us to use Unsharp Mask instead of plain Sharpen,
  and will allow us to handle XCF master files as well as TIFF.
