When option was enabled, `<br />` tags where being added wrongfully
between `<li>` tags, which resulted in malformed html. This commit
prevents this behavior.
Closes#316
This feature enables hashing span elements that should not be touched by
showdown. For instance, `<code>` tags in markdown source should not be
parsed by showdown, so the text inside them remains unchanged.
This is made possible by a new exciting internal feature,
matchRecursiveRegExp.
Closes#196, Closes#175, Partially reverts 5f043ca