Ruby wrapper around David Loren Parsons' discount, a fast,
BSD-licensed C implementation of John Gruber's Markdown plus
some aspects of SmartyPants.  Markdown is a text-to-HTML
conversion language for web writers, inspired by the format
of plain-text e-mail messages.  Markdown allows you to write
in an easy-to-read, easy-to-write plain text format, then
convert it to structurally valid XHTML (or HTML).