also use double-quotes in the whole file

activate sanitizer, sub and sup

This reverts commit 06ab4986, reversing
changes made to 3c4d8d95.

Conflicts:
	Changelog.md

based on the one from the markdown parser, fixes #3553
adding a list of urls for testing the regex in the specs

(fixes #3468)

+ 1 js syntax error

using pageDown Markdown library, fixing autolinking.  created app.helpers.textFormatter, which takes care of text formatting; functions can be called individually throughout the app