Main Thread

Currently, the program spawns threads for all enabled plugins, waits a bit to prove they run, then quits.

This precludes running it in production. Now that we have some working plugins, it would be nice if it was usable as intended, even if not complete. (I am itching to deploy DS18B20.)

Eventually, it might be nice to have proper signaling from the service manager, but for now just sleeping forever unless interrupted (Ctrl-C, etc.) would be sufficient. That is basically how all the existing x-to-MQTT projects work anyway.

Proper signaling is really its own issue we can add & address later.