Removed more old and unused JS code and documented some used ones. (gerrit:136791)
addCommas() & parseIntWH() were/are used by /extensions/wikihow/rcpatrol/rcpatrol.js, but since that's the only caller, that's where the functions in question should reside, not here
emailLink() / setupEmailLinkForm() / the whole "send this article to a friend" stuff is very hairy and needs lots of love
wfTemplate() is used only by wikiHow's CommunityDashboard extension (and, technically speaking, their old HTML5Editor extension, which they no longer use, calls it, too), so removed it
Documented plusone_vote() and added an if() check there because not everyone uses Google Analytics
MediaWiki core: Submitted a changeset (gerrit:137250) to add a new ResourceLoader module for external links CSS & images so that custom skins don't have to duplicate both the CSS and the images all the time, since in most cases custom skin authors either don't need or can't be bothered creating custom external link images.
Added jquery.ui.dialog as a dependency instead of hackily loading a custom build of jQuery (which doesn't even work outside wikiHow, since that particular reference and jQuery UI build exist only on wH)
Fixed various URLs in the JS file to use mw.util.getUrl() instead of assuming that everyone has a null script path (as wikiHow does)
