Update MediaClass.js

- adds "click" and "scroll" triggers to re-evaluate element queries
- separates throttled event triggers from ones that don't require throttling and invokes getMediaFeatures on the unthrottled ones
- adds checks for element.clientWidth > 0 inside mediaLoop to prevent measurement of hidden elements, which can cause hidden elements to incorrectly match width predicates
- adds public "refresh" method to enable manual refresh of the MediaClass when the provided event hooks are not sufficient