Rover: try changing GPS setting to AIRBORNE_4G

this may reduce the GPS latency and improve chicane performance

APMrover2/system.pde

@@ -173,7 +173,7 @@ static void init_ardupilot()
 	// Do GPS init
 	g_gps = &g_gps_driver;
     // GPS initialisation
-	g_gps->init(hal.uartB, GPS::GPS_ENGINE_AUTOMOTIVE);
+	g_gps->init(hal.uartB, GPS::GPS_ENGINE_AIRBORNE_4G);
 
 	//mavlink_system.sysid = MAV_SYSTEM_ID;				// Using g.sysid_this_mav
 	mavlink_system.compid = 1;	//MAV_COMP_ID_IMU;   // We do not check for comp id