[url] URL comparison methods (#20)

It would be really nice if this API included common comparison algorithms for URL. 

In particular, including a way to check if:

* URL A is same origin as B.
* URL A is same as B. 
* URL A subsumes (or includes) B (e.g., http://foo.com/bar/bas subsumes http://foo.com/bar/).  


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Reply to this email directly or view it on GitHub:
https://github.com/webspecs/url/issues/20