LCD multinode proof of concept

Connect an LCD to a master node, plus a 3 node selector resistor ladder, to a slave node hooked up to a thermistor (LM35).

This proof-of-concept builds on the Arduino Due to an Arduino Uno I²C protocol communication as described in this other GitHub repository. A real life implementation can be found here.

Now there is an LCD plus a resistor ladder added to the master node and a thermistor added to the slave node. Temperature is set on the master node and, while no PID over is hooked up, read from the slave node.