To Do
=====
Better error handling for built-in scripts. (non-existent at the moment)

Old - unlikely to be addressed:
Option: locking (uucp? What's the standard?) (Who cares?)

Better testkey (Change stdin mode to raw, update input, system, exec & exit)

getcomchar() (Get one byte from com so a dumb term could be written in a
              script.  Should be done only after testkey)

Polling sucks.  Could this be (major) changed to be interrupt-driven?
(Do people still use non-16550s out there?)

Error reporting doesn't display the line containing the error.