Publish refactoring (#298)

* factoring of the publishing function
* integration of json publishing to MQTT
* receiving and transcode json messages from mqtt
* replace the TRACE runtime condition by a buildtime one so as to decrease program size
* remove retainFlag parameter not necessary for the moment
* Increase the scope of tests for arduino mega and esp32
* Update arduinojson library to 5.13.3
* add macros to choose between simple or json publishing or both
* differentiate build test for ATmega2560
* correct wrong sprintf definition
* change IDE version for continuous integration
* let default warning level in arduino ide
* correct pins for ESP32
* reorganize user_config

ZsensorINA226.ino

@@ -51,6 +51,9 @@ void setupINA226() {
 void MeasureINA226(){
     if (millis() > (timeINA226 + TimeBetweenReadingINA226)) {//retriving value of temperature and humidity of the box from DHT every xUL
         timeINA226 = millis();
+        trc(F("Creating INA226 buffer"));
+        StaticJsonBuffer<JSON_MSG_BUFFER> jsonBuffer;
+        JsonObject& INA226data = jsonBuffer.createObject();
         // Topic on which we will send data
         trc(F("Retrieving electrical data"));
         // Bus Spannung, read-only, 16Bit, 0...40.96V max., LSB 1.25mV
@@ -78,11 +81,10 @@ void MeasureINA226(){
         dtostrf(volt,6,3,volt_c);
         dtostrf(current,6,3,current_c);
         dtostrf(power,6,3,power_c);
-      
-        client.publish(subjectVolttoMQTT,volt_c);
-        client.publish(subjectCurrenttoMQTT,current_c);          
-        client.publish(subjectPowertoMQTT,power_c);  
-        
+        INA226data.set("Volt", (char *)volt_c);
+        INA226data.set("Current", (char *)current_c);
+        INA226data.set("Power", (char *)power_c);
+        pub(subjectINA226toMQTT,INA226data);
     }
 }