- implement cli options:
    1. c case-unsensitive applied to -i. (ignore-list (comma-separated list of
       files) apply to -i, switch from hash to array+strcasecmp.)
    2. o optimize-memory : not implemented.

- Add a file to make an exclusion list (.svn CVS etc...).

- use mime-magic to get content type to allow comparison for one type only.

- zlib, lib unzip, lib unrar

- Report whole directory/subdir/files equality, i.e.
  /home/joke/tar/httpd-2.0.59/ /tmp/httpd-2.0.59/
  Instead of all subfiles/dir of each of these.