View source for Footnotes

Syntax: ##""[[fn text of footnote here]]""##

autogenerates the footnotes at the end of the page, e.g:

%%Text here[[fn text of __first__ footnote here]] and more Words[[fn text of **second** footnote here]]%%
Text here[[fn text of __first__ footnote here]] and more Words[[fn text of **second** footnote here]]


TODO:
  * discuss syntax
  * footnote fail if they contain a line break
  * does not work with included pages