Fix reference as value in addProperty signature

Author: facchinm

src/ArduinoCloud.cpp

@@ -97,8 +97,8 @@ void ArduinoCloudClass::poll()
   _mqttClient.loop();
   uint8_t data[1024];
   int length = Thing.poll(data);
-  if (length) {
-     writeProperties(data, length);
+  if (length > 0) {
+    writeProperties(data, length);
   }
 }
 

src/ArduinoCloudV2.h

@@ -26,7 +26,7 @@ class ArduinoCloudClass {
 
   #define addProperty( v, ...) addPropertyReal(v, #v, __VA_ARGS__)
 
-  template<typename T> void addPropertyReal(T property, String name, permissionType _permission = READWRITE, long seconds = ON_CHANGE, void(*fn)(void) = NULL) {
+  template<typename T> void addPropertyReal(T& property, String name, permissionType _permission = READWRITE, long seconds = ON_CHANGE, void(*fn)(void) = NULL) {
     Thing.addPropertyReal(property, name).publishEvery(seconds).setPermission(_permission).onUpdate(fn);
   }