OnlineMonitor: Pausing, Multiple DUTs, Button Grouping

Some rework of the OnlineMonitor. Now is capable of displaying N DUT canvases (where N is the number of DUTs... 🤙) Canvases are grouped together.

Also, now it has the option to pause and resume monitoring.

What drives me crazy is this weird vertical distance between the buttons:

I've been fighting for two hours with that now but don't find where the issue is. I know how to get rid of it, but then the buttons don't fill the horizontal space, which looks even works:

Maybe I'll still find a way - but not today... ☹

This fixes #41 (closed)