conn: implemented xmpp_connect_raw()

This function is similar to xmpp_connect_client(), but doesn't perform
authentication. Instead, it calls user's connection handler immediately
after establishing the connection. Hence, user can implement own
authendication or registration procedures.

Such a "raw" connection can be useful when user interaction is required
(e.g. Data Forms in XEP-0077, OAuth2).

ChangeLog

@@ -4,8 +4,14 @@
 	- Initial Android support
 	- Resolver returns all SRV records instead of one. Lookup is performed
 	  according to RFC2052.
+	- xmpp_connect_raw() provides access to a xmpp_conn object just after
+	  establishing TCP connection. This allows to implement in-band
+	  registration or authentication mechanisms.
 	- New API:
 		- xmpp_uuid_gen()
+		- xmpp_connect_raw()
+		- xmpp_conn_raw_open_stream()
+		- xmpp_conn_raw_tls_start()
 		- xmpp_conn_get_flags()
 		- xmpp_conn_set_flags()
 		- xmpp_conn_set_keepalive()