* Update specs to use new style shared_examples (@no-reply)
* Loosen hash check on `Node#==` (@no-reply)
* Fix validate! in Value to return self, as is documented.
* Add Pattern#valid? to improve on Statement#valid? for legitimate patterns.
* Improve Query#validate! to validate patterns, not require the first pattern to not be optional, and modernize check for appropriate partition of required and optional patterns.