Add XEP-0280 support

src/xmpp/xmpp.h

@@ -172,6 +172,8 @@ void presence_update(resource_presence_t status, const char * const msg,
 gboolean presence_sub_request_exists(const char * const bare_jid);
 
 // iq functions
+void iq_enable_carbons();
+void iq_disable_carbons();
 void iq_send_software_version(const char * const fulljid);
 void iq_room_list_request(gchar *conferencejid);
 void iq_disco_info_request(gchar *jid);