Refactor, move APRS text message parsing to a function
Added packet length checks in message parsing
Disallow a set of message destinations, old status messages sent by old aprsds.
Matches javaprssrvr functionality now.
"javaMSG", /* old aprsd */
"JAVATITLE", /* old aprsd */
"JAVATITL2", /* old aprsd */
"USERLIST", /* old aprsd */
"KIPSS", /* APRS+SA */