Pass JSHint on resources/{mediawiki.api,jquery,mediawiki}/*

Pass JSHint on resources/{mediawiki.api,jquery,mediawiki}/*

Notes:
* JSHint stuff
* Code conventions
* jQuery best practices
* mediawiki.debug:
  - Append a text node instead of html. Though .append()
    does check if it looks "like" not-html and creates a text
    node, this is not more a sanity/security thing than a
    reliable documented feature. http://api.jquery.com/append/ :
    "HTML string, DOM element(s) or jQuery object".

While at it:
* Update .jshintignore to also cover:
  - resources/mediawiki.libs/CLDRPluralRuleParser.js
* Update .jshintrc to set onevar back to true (was set to false
  temporarily but not removed).
* Fix files in resources/mediawiki and resources/jquery as well.
  These dirs where already covered, perhaps these were missed or
  recently introduced, again.
* Add missing dependencies:
  jquery.highlightText -> jquery.mwExtension ($.escapeRE)
  jquery.tablesorter -> jquery.mwExtension ($.escapeRE)
  mediawiki.page.watch.ajax -> jquery.mwExtension ($.escapeRE)

Change-Id: I30a55717d0963ce23e51cef1f1df9e549e4c232e