Tool zum Nachrichten lesen: https://github.com/eclipse/paho.mqtt-spy
Installation auf dem Raspberry Pi
https://mosquitto.org/2013/01/mosquitto-debian-repository/
http://jpmens.net/2013/09/01/installing-mosquitto-on-a-raspberry-pi/
mosquitto_sub -t "topic/path"
https://www.heise.de/developer/artikel/Kommunikation-ueber-MQTT-3238975.html