Organise files in a directory into subdirectories based on their extensions.

Usage:
  cleanup [-d | -s] [-r] <dir>
  cleanup -h

Options:
  -d, --dry-run     Just display the changes that would be made, without
                    actually doing anything.
  -s, --silent      Do not display information while performing operations.
  -r, --revert      Revert previous cleanup of the directory.
  -h, --help        Display this help text.