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

lib/ArduinoJson/CHANGELOG.md

@@ -1,6 +1,21 @@
 ArduinoJson: change log
 =======================
 
+v5.13.3
+-------
+
+* Improved float serialization when `-fsingle-precision-constant` is used
+* Fixed `JsonVariant::is<int>()` that returned true for empty strings
+* Fixed `JsonVariant::is<String>()` (closes #763)
+
+v5.13.2
+-------
+
+* Fixed `JsonBuffer::parse()` not respecting nesting limit correctly (issue #693)
+* Fixed inconsistencies in nesting level counting (PR #695 from Zhenyu Wu)
+* Fixed null values that could be pass to `strcmp()` (PR #745 from Mike Karlesky)
+* Added macros `ARDUINOJSON_VERSION`, `ARDUINOJSON_VERSION_MAJOR`...
+
 v5.13.1
 -------