multimarkdown lacking support for definition lists

[joeyh]

The definition lists documented in http://fletcherpenney.net/multimarkdown/users_guide/multimarkdown_syntax_guide/ arn't supported.

Test program:

use Text::MultiMarkdown 'markdown';
print markdown("
Apple
: Pomaceous fruit of plants of the genus Malus in
the family Rosaceae.
: An american computer company.

Orange
: The fruit of an evergreen tree of the genus Citrus.
");