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).

strophe.h

@@ -169,6 +169,7 @@ typedef struct _xmpp_stanza_t xmpp_stanza_t;
 /* connect callback */
 typedef enum {
     XMPP_CONN_CONNECT,
+    XMPP_CONN_RAW_CONNECT,
     XMPP_CONN_DISCONNECT,
     XMPP_CONN_FAIL
 } xmpp_conn_event_t;
@@ -238,6 +239,14 @@ int xmpp_connect_component(xmpp_conn_t * const conn, const char * const server,
                            unsigned short port, xmpp_conn_handler callback,
                            void * const userdata);
 
+int xmpp_connect_raw(xmpp_conn_t * const conn,
+                     const char * const altdomain,
+                     unsigned short altport,
+                     xmpp_conn_handler callback,
+                     void * const userdata);
+int xmpp_conn_raw_open_stream(xmpp_conn_t * const conn);
+int xmpp_conn_raw_tls_start(xmpp_conn_t * const conn);
+
 void xmpp_disconnect(xmpp_conn_t * const conn);
 
 void xmpp_send(xmpp_conn_t * const conn,