Renamed default_transform function to defaultTransform.
XML-style empty tags were not recognized correctly when the / was not preceded by whitespace. Also made the regex a little more strict, so that </br/> wouldn't be seen as a valid tag.
Merge branch 'master' into extra

Conflicts:
	PHP Markdown Extra Readme.text
Added multiple footnote backlinks when footnotes have multiple references.
Merge branch 'extra' into lib

Conflicts:
	Readme.md