Make this an abstract GObject. Tweak some of the interfaces around a

Make this an abstract GObject. Tweak some of the interfaces around a

	* libsoup/soup-auth.c: Make this an abstract GObject. Tweak some
	of the interfaces around a little bit.

	* libsoup/soup-auth-basic.c: subclass for Basic auth

	* libsoup/soup-auth-digest.c: subclass for Digest auth

	* libsoup/soup-auth-ntlm.c: subclass for NTLM auth. Move all of
	the code from soup-ntlm.c here, and make it private.

	* libsoup/soup-ntlm.c: gone

	* libsoup/soup-misc.h: Remove the definition of SoupAuthType from
	here, and change the signature of SoupAuthorizeFn.

	* libsoup/soup-context.c: Use g_object_unref to free auths, use
	methods instead of directly access private fields.

	* libsoup/soup-queue.c: Likewise

	* libsoup/soup-server-auth.c (soup_server_auth_free): Remove all
	NTLM references. We have no plans to implement server-side NTLM
	auth.

	* tests/auth-test.c (identify_auth): Update for auth api changes