resolves widget sort issue, closes #6
Bug #2180, Optionally extract the quiz ID from the URL - SlickQuiz

* (Commit attempt 2, https://github.com/jewlofthelotus/SlickQuiz-WordPress fork)
* A backwards compatible change, that guards against mis-spellings
* Shortcode pattern(s):  [slickquiz id=url], [slickquiz id=(url|uri|-1)]
* https://plugins.trac.wordpress.org/ticket/2180
Bug #58, New WP action "slickquiz_save_quiz" - PHP component

* As detailed in the bug/ issue report, a way to save extra data
* https://github.com/jewlofthelotus/SlickQuiz-WordPress/issues/58
Bug #58, Set a callback to add extra data sent with Ajax POST - JS

* Needs work!
* Javascript to complement the PHP modifications in previous commit
* New public function `$.fn.setPreSaveQuiz(function () { return extra })`
Bug #58, Tidy up the Javascript callback mechanism

* Public JS function `$.fn.setPreSaveQuiz(function ( return extra ) {})`
adding documentation around presave stuff
Merge branch 'nfreear-nfreear-fixes'; closes #58