[aprssig] APRS-IS: frames bypassing server filter

[John Langner WB2OSZ]

There is already a way for IGate stations to identify themselves as two way
or receive only.

>From  http://www.aprs-is.net/q.aspx 


qAR - Packet is placed on APRS-IS by an IGate from RF. The callSSID
following the qAR is the callSSID of the IGate.


qAO - (letter O) Packet is placed on APRS-IS by a receive-only IGate from
RF. The callSSID following the qAO is the callSSID of the IGate. Note that
receive-only IGates are discouraged on standard APRS frequencies. Please
consider a bidirectional IGate that only gates to RF messages for stations
heard directly.