Updates for MQTT device users

[owlcms]

If you are using MQTT devices (blue-owl or owlcms-firmata) there is a new feature available for testing in pre-release 61.0.0-rc01.  You can now see what devices are connected by going to the Session / Button Testing page.

If you use owlcms-firmata, you should update to release 2.4.0 using the owlcms-firmata control panel to make better use of this feature (prior releases created unneeded connections that make the output harder to figure out)