Plane: log NTUN:ArspdErr airspeed error (in meters)

ArduPlane/Log.cpp

@@ -281,6 +281,7 @@ struct PACKED log_Nav_Tuning {
     int16_t altitude_error_cm;
     float   xtrack_error;
     float   xtrack_error_i;
+    float   airspeed_error;
 };
 
 // Write a navigation tuning packet
@@ -294,7 +295,8 @@ void Plane::Log_Write_Nav_Tuning()
         nav_bearing_cd      : (int16_t)nav_controller->nav_bearing_cd(),
         altitude_error_cm   : (int16_t)altitude_error_cm,
         xtrack_error        : nav_controller->crosstrack_error(),
-        xtrack_error_i      : nav_controller->crosstrack_error_integrator()
+        xtrack_error_i      : nav_controller->crosstrack_error_integrator(),
+        airspeed_error      : airspeed_error
     };
     DataFlash.WriteBlock(&pkt, sizeof(pkt));
 }
@@ -486,7 +488,7 @@ const struct LogStructure Plane::log_structure[] = {
     { LOG_CTUN_MSG, sizeof(log_Control_Tuning),     
       "CTUN", "Qcccchhh",    "TimeUS,NavRoll,Roll,NavPitch,Pitch,ThrOut,RdrOut,ThrDem" },
     { LOG_NTUN_MSG, sizeof(log_Nav_Tuning),         
-      "NTUN", "Qfcccff",  "TimeUS,WpDist,TargBrg,NavBrg,AltErr,XT,XTi" },
+      "NTUN", "Qfcccfff",  "TimeUS,WpDist,TargBrg,NavBrg,AltErr,XT,XTi,ArspdErr" },
     { LOG_SONAR_MSG, sizeof(log_Sonar),             
       "SONR", "QHfffbBf",   "TimeUS,DistCM,Volt,BaroAlt,GSpd,Thr,Cnt,Corr" },
     { LOG_ARM_DISARM_MSG, sizeof(log_Arm_Disarm),