TODO

- A bug with -S shows wrong results.

- A bug causes the following behavior:

  $ fdupes --symlinks testdir
  testdir/with spaces b
  testdir/with spaces a

  testdir/zero_b
  testdir/zero_a

  testdir/symlink_two
  testdir/twice_one

  $ cp testdir/two testdir/two_again
  $ fdupes --symlinks testdir
  testdir/two_again
  testdir/two
  testdir/twice_one
  testdir/symlink_two

  testdir/with spaces b
  testdir/with spaces a

  testdir/zero_b
  testdir/zero_a

  ** This is not the desired behavior. Likewise:

  $ fdupes testdir
  testdir/with spaces b
  testdir/with spaces a

  testdir/zero_b
  testdir/zero_a

  testdir/twice_one
  testdir/two

  $ fdupes --symlinks testdir
  testdir/with spaces b
  testdir/with spaces a

  testdir/zero_b
  testdir/zero_a

  testdir/symlink_two
  testdir/twice_one

- Option -R should not have to be separated from the rest,
  such that "fdupes -dR testdir", "fdupes -d -R testdir",
  "fdupes -Rd testdir", etc., all yield the same results.

- Add option to highlight or identify symlinked files (suggest
  using --classify to identify symlinks with @ suffix... when
  specified, files containing @ are listed using \@).

- Consider option to match only to files in specific directory.

- Add a way to store stat() info + inital and full hashes for
  explicit loading in future runs to speed up repeated calls to
  the program.

- Add an option to exclude files in the same directory from being
  matched. This should be extensible so that various exclusion
  criteria can be added later.
  - Also add code to make directory ordering of pair matching more
    stable; for instance, if dirs 'foo' and 'bar' are specified,
    always put 'foo' at the start of the dupe set (which makes it
    take precedence over 'bar' in this example.)

- The way that duplicates are sorted does not seem to work properly. The
  sorting needs to be separated into its own function that sorts fully.
  As it stands, sorting is only correct on specific match pairs and is
  sometimes overridden by other match pairs to mess up the sort.

- The --xsize option can be improved. Instead of simply specifying an
  exclusion size minimum, the option should offer multiple ways to
  specify allowed file sizes. Examples:
  - '--xsize=-1M' only examine files 1 MB or less
  - '--xsize=+3M' only examine files 3 MB or greater
  - '--xsize=512-1024' only examine files between 512 and 1024 bytes
  - '--xsize=1M-3M,+20M' examine files 1-3 MB and >20 MB in size