Support for Shared Subscriptions
As part of #75, support for shared subscriptions has been added. Even though this is an MQTT 5 feature, all common brokers seem to support it for MQTT 3.1 connections as well. This means that connecting with multiple clients using a topic of the form $share/<group>/<topic>
will have the broker distribute messages to all of those clients where the group name is the same. More details about shared subscriptions can be found on the HiveMQ blog.