[aprssig] X-APRS: a new protocol in APRSdroid

[Steve Dimse]

Just noticed this from the web site:

> Implementation note: In legacy APRS, the leading < character in the payload might be interpreted as a "Station Capabilities" Data Type Identifier. Legacy clients MUST NOT attempt to interpret APRS packets with a to-call of XAPRS.
> 
If you are going to use the current APRS-IS you CANNOT make demands on legacy applications. If you need to do something on the APRS-IS that is incompatible with current implementations you must use the User Defined Packet type. To do otherwise would be the worst kind of QRM on a long-standing and successful Amateur Radio system.

Steve K4HG