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/Adafruit_TSL2561/README.md

@@ -1,7 +1,10 @@
-#Adafruit TSL2561 Light Sensor Driver #
+# Adafruit TSL2561 Light Sensor Driver  [![Build Status](https://travis-ci.org/adafruit/Adafruit_TSL2561.svg?branch=master)](https://travis-ci.org/adafruit/Adafruit_TSL2561)
 
 This driver is for the Adafruit TSL2561 Breakout, and is based on Adafruit's Unified Sensor Library (Adafruit_Sensor).
 
+<img src="https://cdn-shop.adafruit.com/970x728/439-00.jpg" height="300"/>
+
+
 The driver supports manual or 'auto' gain. Adjusting the gain allows you to make the sensor more or less 'sensitive' to light (depending on if you are indoors or outdoors, for example):
 ```
 tsl.setGain(TSL2561_GAIN_1X);      /* No gain ... use in bright light to avoid sensor saturation */
@@ -9,7 +12,7 @@ tsl.setGain(TSL2561_GAIN_16X);     /* 16x gain ... use in low light to boost sen
 tsl.enableAutoGain(true);          /* Auto-gain ... switches automatically between 1x and 16x */
 ```
 
-The driver also supports as automatic clipping detection, and will return '0' lux when the sensor is saturated and data is unreliable.
+The driver also supports as automatic clipping detection, and will return '65536' lux when the sensor is saturated and data is unreliable. tsl.getEvent will return false in case of saturation and true in case of valid light data.
 
 ## About the TSL2561 ##
 
@@ -44,4 +47,4 @@ Light sensors will always report units in lux, gyroscopes will always report uni
 
 Adafruit invests time and resources providing this open source code.  Please support Adafruit and open-source hardware by purchasing products from Adafruit!
 
-Written by Kevin (KTOWN) Townsend for Adafruit Industries.
+Written by Kevin (KTOWN) Townsend for Adafruit Industries.