AC_PosControl: get_accel_target returns const ref

libraries/AC_AttitudeControl/AC_PosControl.h

@@ -180,14 +180,14 @@ public:
     float get_pitch() const { return _pitch_target; }
 
     // get_leash_xy - returns horizontal leash length in cm
-    float get_leash_xy() { return _leash; }
+    float get_leash_xy() const { return _leash; }
 
     /// get_pos_xy_kP - returns xy position controller's kP gain
     float get_pos_xy_kP() const { return _p_pos_xy.kP(); }
 
     /// accessors for reporting
-    const Vector3f get_vel_target() { return _vel_target; }
-    const Vector3f get_accel_target() { return _accel_target; }
+    const Vector3f& get_vel_target() const { return _vel_target; }
+    const Vector3f& get_accel_target() const { return _accel_target; }
 
     static const struct AP_Param::GroupInfo var_info[];