[aprssig] New ##LNKn-N and SSn-N standards for consistency

[Robert Bruninga]

To keep users informed of the changes by this new n-N
paradigm, we should label our new digis in a consistent
manner for the benefit of the users.  I suggest:

S overlay for SSn-N's             "R,W,SSn" in BText
K overlay for LNKn-N's,          "R,W,##Kn" in BText for interstate ##
X overlay for dual LNKn-N's   "R,W,##Kn,81Kn" for I-90 and I-81
L overlay for LAN/LINKn-N's "R,W,##Kn,SSn" for I-90 and State

I expect most if not all such digis will actually be just the X or L 
variety unless they want to still support WIDEn-N, then they would
use the S or K for the new n-N usage and add Wn in the BText
to show that it still supports WIDEn-N.  For example:

K overlay for  "R,W,##Kn,Wn" in BText for interstate ## and WIDEn-N
S overlay for  "R,W,SSn,Wn"   in BText for State SS and WIDEn-N


Of course we keep the existing overlays:

R  for RELAY only digis
W  for WIDE or RELAY,WIDE only digis
T   for RELAY,WIDE with    callsign substitution Tracing (PacComm
ROMS)
N  overlay for WIDEn-N's,  "R,W,Wn" in BText
U  for UIdigi 
D  for DIGI_NED

de WB4APR, Bob