[aprssig] Garmin emulation

[Scott Miller]

Just wanted to see what everyone thinks of an idea I had.  I've been working
a lot with the Garmin binary protocol for my new project, and in the course
of the development process came up with a test program to emulate functions
of a Garmin GPS.  I found that by connecting a null modem cable between two
serial ports, I could transfer waypoints to and from any mapping program
that supports Garmin protocol - which is most of them.

I think something like this might be easiest to deploy as a UI-View plugin,
at least initially.  It wouldn't be completely seamless from the mapping
side, since you'd have to manually start transfers, but it might open up a
lot more software options.

I'm not looking forward to writing a virtual com port driver, though.  And
all of the commercial loopback drivers I've seen start at $100.  In
Unix/Linux it's absolutely trivial to set one up, but it could be a real
pain in Windows.  If anyone knows of a cheap (or free) solution to create
fake com ports, let me know.

Scott
N1VG