add "realm" field to the struct. (SoupAuthClass) remove "get_realm"

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