New serial code

[James S. <jsi...@tr...>]

To bring to peoples attention but I the current code seport.c has been
moved over to serport_old.c. serport_old.c is the code to register a
serial device to a serial line. serport.c is going to be a rewrite using a
new serial layer loosly based on Russel kings serial_core.c code. I
haven't had the chance yet to play with that code.