er originally licensed under GPL
 Lars Stollenwerk has agreed to relicense the code in this file under MPL (Oct 2009)

 to use:
 1) call vt100_init_terminal
 2) for every 'inbound' data (received from remote host), call "vt100_process_inbound_char" - this will update the screen
 3) pass every keypress into vt100_transform_outbound_char. on return from this call,
      Y = 0 means don't send anything as a result of this keypress
      Y = 1 means A contains single character to send to remote host
  