[Xastir] dual port TNC

[Jason KG4WSV]

The problem with ax25 solutions (and it's a show-stopper for me) is
that it's linux-only - I run macs.  My theoretical MKISS daemon would
be independent of ax25 kernel support.

I've got an arduino mega (an ATmega1280, 4 hardware UARTs), and an
ethernet interface for it.  It would be simple to implement a socat
style network interface for 4 devices using the mega + ethernet
shield.  This would eliminate the need for an MKISS daemon.

Of course, one could probably implement the network interface with
APRS-IS server style connections and a non-KISS TNC interface, but
that creates an igate configuration issue getting traffic from xastir
to RF.

-Jason
kg4wsv