[BRLTTY] display key commands intermittently not processed - Baum driver

[Jason White]

Under BRLTTY 5.3.1 but not 5.2, commands issued via the display keys on a Baum
SuperVario 40 appear to be simply dropped. Also, sometimes commands are
repeated even when the key was pressed only once.

To debug this further, we need a packet log. I've cloned the Git repository.
There used to be a source line that needed to be changed in the Baum driver to log
packets, but I can't find it, so perhaps the logging settings have changed.

I'm using a USB interface. I've also tested 5.3.1 with a Focus 40 Blue display
owned by my employer, and this combination is working reliably. As an aside,
the Focus 40 Blue is well supported under all of the operating systems that
I've tried: Linux, OS X, iOS, MS-Windows and Chrome OS, although the quality
of braille support varies significantly depending on operating system and
screen reader.