Cross-reference jQuery.is*() methods from Testing Types

[scottgonzalez]

The bottom of http://learn.jquery.com/javascript-101/testing-type/ says "jQuery also offers utility methods to help determine the type of an arbitrary value." but doesn't link to anything or mention what methods are available. There should be an article that explains the jQuery.is*() and jQuery.type() methods, and that page should be linked from this page.

[arthurvr]

core/utility-methods is a better place for this, IMHO. Update: pr #597