[aprssig] Point-to-point telemetry addressing

[scott at opentrac.org]

> However, neither of these appear to work.  The only addressing that 
> seems to work is APRS,WIDE2-2, but that only works from time to time, 

APRS should not be part of your path, unless you're using a program that
takes the first entry as the destination callsign.  I forget which ones do
that.  Do you have an example of one of your packets after it's been
digipeated?  That might tell you what's going on.

Scott
N1VG