[Xastir] $PGRMW waypoint support

[Curt, WE7U]

xastir/src/gps.c:create_garmin_waypoint()

Is called from xastir/src/db.c:data_add().  Here is the relevant
code from data_add() so you can see when the waypoints come into
play:

-------------------------------
/* check ranges */
if ((distance > atof(prox_min)) && (distance < atof(prox_max))) {

   //fprintf(stderr,"Station within proximity circle, creating waypoint\n");
   create_garmin_waypoint(p_station->coord_lat,
     p_station->coord_lon,
     p_station->call_sign);

   if (sound_play_prox_message) {
     xastir_snprintf(station_id, sizeof(station_id),
       "%s < %.3f %s",p_station->call_sign,
       distance,
       english_units?langcode("UNIOP00004"):langcode("UNIOP00005"));
     statusline(station_id,0);
     play_sound(sound_command,sound_prox_message);
     /*fprintf(stderr,"%s> PROX distance * %f\n",p_station->call_sign, distance);*/
   }
}
-------------------------------

-- 
Curt, WE7U.                         <http://www.eskimo.com/~archer>
    APRS:  Where it's at!                    <http://www.xastir.org>
   Lotto:  A tax on people who are bad at math. - unknown
Windows:  Microsoft's tax on computer illiterates. - WE7U.
The world DOES revolve around me:  I picked the coordinate system!"