Don't open serial port when starting BDM over USB
Don't open serial port when starting BDM over USB

Previously the word "bdm" would set the baud rate of the serial port -
which it ignores. I don't see this problem with "chat" because there are
two versions of it: one for serial chat (in chat-host.mu4) and one for
USB chat (in chat-usb-host.mu4).

nickhen/muforth,nickhen/muforth