url-digest-auth QOP implementation

[Jarno Malmari]

Greetings.

I've partially implemented the qop=auth in HTTP Digest Authentication
(RFC 2617) for the Emac Url package.

Change was motivated by running into servers that had dropped backward
compatibility for qop-less clients.

In order to implement the qop=auth I needed to refactor the old
url-digest-auth* functions. I added some tests to check I don't break
too much of the old functionality.

Git summarizes the change as follows:
lisp/url/url-auth.el             | 391
++++++++++++++++++++++++++++++++++++++++++++++++-----------------
test/automated/url-auth-tests.el | 293
++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 582 insertions(+), 102 deletions(-)

If we were to get these changes in, to who should I send the patches for
a review?

Other ideas and concerns are welcome also, of course.

Thanks

-- 
Jarno Malmari