GPSGlitch: reduce radius to 2m

libraries/AP_GPS/AP_GPS_Glitch.h

@@ -14,7 +14,7 @@
 #include <AP_GPS.h>
 
 #define GPS_GLITCH_ACCEL_MAX_CMSS   1000.0f // vehicle can accelerate at up to 5m/s/s in any direction
-#define GPS_GLITCH_RADIUS_CM        500.0f  // gps movement within 5m of current position are always ok
+#define GPS_GLITCH_RADIUS_CM        200.0f  // gps movement within 2m of current position are always ok
 
 /// @class	GPS_Glitch
 /// @brief	GPS Glitch protection class