Kingswood Monitor outside environment sensor firmware

This is the firmware for the Kingswood LoRa transmitter.

Runs on a feather32u4 RFM9X under arduino.

Reads temperature and humidity data from a DH22. Constructs a JSON object from the data, e.g.

{"sensor":"greenhouse","temperature":3.3,"humdity":99.9,"voltage":3.764062}

Implements sleep functionality to conserve battery power.