Add support for a refresh command

src/main.cpp

@@ -268,6 +268,8 @@ void processCommandMessage(const String &topic, const String &payload) {
 
         startFetchingPosition(shades[i].ID, -1);
         timer.in(100, sendFetchPosition, shades[i].ID);
+      } else if (payload == "REFRESH") {
+        startFetchingPosition(shades[i].ID, -1);
       }
     }
   }