[Rcxemul-discussion] Update on serial comms

[David E. <d.a...@du...>]

I've managed to get serial comms working (albeit very flakily). The
emulator will receive messages and seems to deal with most of them
appropriately. I have hacked the lejos firmware downloader so that it
will communicate with the emulator, and so far the emulator has
successfully replied to a request to see if it's alive, and has worked
its way (very slowly) through the download of the firmware image.

I haven't verified that the firmware has been successfully downloaded -
I need a better debugging framework to do this. The download fails when
it attempts to unlock the firmware. No reply is received from the
emulator. Again, I need a better way of debugging to find out why.