[aprssig] Upgrading the "T" digis to "P" digis

[Robert Bruninga]

> About 70 stations are using 'T' as digipeater overlay, 
> this seems to be digipeaters supporting TRACEn-n only.

I offer this correction.  The T overlay's are the PacComm TNC's
that only Support TRACE only (not TRACEn-N).  These digis can
only do Callsign substitution, they cannot do any n-N multi-hop
functions.  They are Obsolete, but can still be marginally used
in the New-N Network by giving them these FOUR discrete paths:
WIDE1-1, WIDE2-2, WIDE2-1, and WIDE3-3

These PacComm digis will then do a callsign substitution on
those exact calls, and will still be somewhat usable in a New-N
network at least for the first and second hop for mobiles that
use the path of WIDE1-1,WIDE2-1.  When they are configured this
way, they become "P" overlay digis.  But "T" by themselves are
completely obsolete and of no value in a New-N system.

> These stations (and all other unknown) are marked with the 
> orange symbol.
> 
>      986 overlay="S">
>      752 overlay="/">
>      243 overlay="N">
>      130 overlay="1">
>       92 overlay="U">
>       81 overlay="L">
>       70 overlay="T">