Footnotes feature. It looks like MultiMarkdown Footnotes Syntax:

    Here is some text containing a footnote.[^somesamplefootnote]

    [^somesamplefootnote]: Here is the text of the footnote itself.

- http://daringfireball.net/2005/07/footnotes
- https://github.com/fletcher/MultiMarkdown/wiki/MultiMarkdown-Syntax-Guide#wiki-footnotes
- http://six.pairlist.net/pipermail/markdown-discuss/2005-August/001442.html
- http://six.pairlist.net/pipermail/markdown-discuss/2005-August/001480.html
Fix: Add ref links for footnotes
Fix footnotes regex. Fix footnotes workflow.
Update footnote regex pattern
multiple fixes to get footnotes working. see #351.