Once 5.2 goes stable, we can remove 5.1 specific code / documentation and
make this module fully 5.2-only.

Possible checks to add:

- Limit the amount of URL's that a user can use in a single post;

- http://translate.google.com/translate?hl=en&sl=fr&u=http%3A%2F%2Fconseil-recherche-innovation.net%2Findex.php%2F2006%2F03%2F23%2F61-un-antispam-simpliste-pour-dotclear

Possible CAPTCHA types to add:

- A simple trivia quiz CAPTCHA type.
  ("what's larger: elephant or mouse?");

- A captcha for the non-graphical captcha that's in the modules forum
  and made by Sheik.

Features:

- Keep track of spam events by logging actions taken by this module;

- Add an option to give a CAPTCHA class a chance to create its own
  settings screen.

- Storage of cache data in the db, not files.

- Keep track of already solved CAPTCHAs when using preview.

