Using Serial1 with USB disconnected

Well, I've just checked up on the logic for this, and it's:

• When USB is plugged in, change console device to be USB
  
• When USB is unplugged, if the console device is USB, change it to Serial1
  
  

Unfortunately there's no callback for when USB is connected or disconnected, so it might be best to just do something like:

setInterval(function() {
  if (process.env.CONSOLE=="Serial1") setConsole(LoopbackA);
}, 1000);