MQTT subscriptions stop working after broker restarts

If the MQTT broker restarts while Synchronet is running, then the subscriptions that should handle sbbs/+/node/+/input, sbbs/+/host/+/server/term/recycle, etc, stop working.

From the bit I've read, it seems like two suggested solutions are:

1. Don't use clean sessions, so subscriptions are remembered after reconnecting, or
2. Move subscription calls to the connect callback, so they're re-subscribed after reconnecting