mqttOnmessage! now return topic

src/interface.jl

@@ -277,11 +277,10 @@ function mqttOnmessage!(client::mqttClient)
     else
         for i = 1:nmessages
             pkg = take!(get_messages_channel()) # take new arrival package
-            topic = pkg.topic
             # sptoptic = split(topic, "/")
             payload = vecToDict(pkg.payload)    # payload in Dict format
             
-            return payload
+            return pkg.topic, payload
         end
     end
 end