add "realm" field to the struct. (SoupAuthClass) remove "get_realm"
* libsoup/soup-auth.h (SoupAuth): add "realm" field to the struct.
(SoupAuthClass) remove "get_realm" virtual method.
* libsoup/soup-auth.c (soup_auth_new_from_header_list): Parse the
WWW-Authenticate/Proxy-Authenticate header here, set realm, and
pass the params hash to the construct method.
(soup_auth_get_info): Return an identifier for the auth:
"SCHEME:REALM"
* libsoup/soup-auth-basic.c:
* libsoup/soup-auth-digest.c: update
* libsoup/soup-session.c (invalidate_auth, update_auth_internal):
use soup_auth_get_info().
svn path=/trunk/; revision=934