[Coco] virtual modem serial -> tcpip thing

[Aaron Wolfe]

Last night I took the DriveWire 4 server, stripped out the DriveWire
part and rearranged things so that you can map virtual modems directly
to serial ports.  This allows you to use any number of serial ports on
a host to provide that number of virtual modems that respond to
standard hayes AT commands and allow you to 'dial' via telnet to an
internet site.  If you use a term program in DECB, it's one way to get
your CoCo's serial port talking to the internet.  There is actually
nothing CoCo specific about this new server, it just makes a telnet
connection look a lot like a hayes compatible modem on a serial port,
so might be useful for other purposes as well.

There are other programs that do this already, although I've not seen
anything that implements the hayes command set as fully as the
DriveWire virtual modems do, and the ability to service multiple
concurrent serial ports might be unique.  Since like DriveWire this
server can run on over 30 platforms, maybe it would be useful in some
niche situations.

I'm going to add the source to the DriveWire sourceforge CVS.  If
there is interest in such a thing, I'll package it up and make
available for public download somewhere.  I haven't added incoming
connection support, but porting the incoming pool system from DW to
this server would not be difficult if that is useful to someone.

-Aaron