Latest NTLM snapshot code, courtesy of kinkie and robert.

Latest NTLM snapshot code, courtesy of kinkie and robert.

<quote>
It's been a while coming... but Kinkie and I now have
probably-production ready NTLM code. It's gone past 1.5 million requests
without failing. The attached patch is a rollup of many minor fixes and
some enhancements:

* Digest: fix crash on shutdown
* ACL: New type max_user_ip to replace authenticate_ip_is_strict.
* ACL: Authenication refactored, to separate authentication and
  authorisation as well as allow 'lazy auth' where authentication is
  triggered by the presence of an authentication using ACL, not
  necessarily "proxy_auth". I.e. using max_user_ip will trigger
  authentication even if no proxy_auth acl's are defined.
* Authentication: API for schemes extended to allow handling duplicate
  authentication on a authenticated _connection_ (yes NTLM again).
* Authentication: Authentication API extended to allow multiple IP's per
  auth_user, and to allow authentication as an orthogonal process to
  authorisation.
* NTLM: many minor races fixed. Should prevent the "Direction before
  ..." errors and the "Duplicate auth" + login popup bug.
* Delay pools: Support authentication (Non-NTLM)in delay pools acl's.
  Beginnings of NTLM support for same.
* Helpers: Stateful helper bugfixes to prevent negative deferred helper
  counts (which prevented ntlm challenge refreshing).
* configure: detect two more headers for NTLM compilation on some
  platforms.

</quote>