DLX is essentially a Ruby port from the Java DLX library created by Stan Chesnutt
(http://www.bluechromis.com/stan/chesnutt.html).

If you want to know more about Dancing Links please read the original document from
Donald Knuth's website (http://www-cs-faculty.stanford.edu/~knuth/preprints.html document P159) or
if you are italian have a look at my website (http://sandropaganotti.com).

At the moment I've commented only a fraction of the full code (apologize!). I'll cover the whole
library ASAP.

Sandro Paganotti
http://www.sandropaganotti.com