Update wiki link
Merge pull request #1704 from erikdesjardins/wiki

readme: Update wiki link (now points to reddit)
bugfix for occasional error message in hover module
batching of classlist changes to HTML and BODY tags, addresses (as best as I reasonably can) this helpful bug report:

https://bugzilla.mozilla.org/show_bug.cgi?id=801977

there will still be classes added to body or html after runtime etc, but most only take place upon user interaction (e.g. when you open the big editor, etc) - this should significantly reduce repaints
only draw the big editor if it's actually called by the user.

also fixed a bug where character limit was displaying as null
whoops, moved event listeners, renamed addBigEditor function as now it only adds the listener.