Auto discovery deactivation at runtime by MQTT command (#856)

and switch automatic creation for it in HASS (by autodiscovery :-)

main/ZgatewayRF.ino

@@ -98,7 +98,8 @@ void RFtoMQTT() {
 
     if (!isAduplicateSignal(MQTTvalue) && MQTTvalue != 0) { // conditions to avoid duplications of RF -->MQTT
 #  if defined(ZmqttDiscovery) && !defined(RF_DISABLE_TRANSMIT) //component creation for HA
-      RFtoMQTTdiscovery(MQTTvalue);
+      if (disc)
+        RFtoMQTTdiscovery(MQTTvalue);
 #  endif
       pub(subjectRFtoMQTT, RFdata);
       // Casting "receivedSignal[o].value" to (unsigned long) because ArduinoLog doesn't support uint64_t for ESP's