Record correct normalized href attribute for extlinks.

* Fixes RTing of snippets like [http://foo.com?a=a&035;b bar]
* Also got rid of stale dataAttribs.gc attribute from tokenizer.
* 3 more wt2wt tests green.
* Fixes RTing of en:Maverick House Publishers.

Change-Id: Ie3aba841405717a22bffca9448ae58568a53bdd7
Merge "Record correct normalized href attribute for extlinks."