Footnote support
Merge pull request #62 from myitcv/footnote_support

Footnote support
Add folding support

Closes #10.
Add a README

Closes #66.
Allow multi-char footnote labels.
Footnote doesn't have to be at the line end.
Indent the footnotes also.
Merge pull request #67 from sencer/master

Improve footnotes
Conceal bold and italic markers

References #9.