Connecting DS18B20 temperature sensor to emonTx shield

As it stands, the emonTx Shield sketch listed there is not compatible with the emonPi running with JeeLib, but it would probably have been easier to start with this and swap the RFM Native library (rfm69nTxLib) for the ‘old standard’ library (rfmTxLib) which is compatible with the older emonPi/emonBase.