MIMIC implements MQTT 6

Skipping the latest MQTT 5, MIMIC MQTT Simulator now supports the
yet-to-be-defined MQTT 6 standard.

Happy April Fool's Day!

In all seriousness, MIMIC is the first MQTT 5 simulator to implement the
latest MQTT 5.

Try it out at http://mqttlab.iotsim.io/mqtt5/