AC_Avoidance: add adjust_velocity that accepts Vector3f for convenience

We should actually modify this function to scale back the z axis in order to avoid breaching the vertical fence.  Currently breaching the vertical fence is handled within the position controller which is inconsistent.

libraries/AC_Avoidance/AC_Avoid.cpp

@@ -37,6 +37,15 @@ void AC_Avoid::adjust_velocity(const float kP, const float accel_cmss, Vector2f
     }
 }
 
+// convenience function to accept Vector3f.  Only x and y are adjusted
+void AC_Avoid::adjust_velocity(const float kP, const float accel_cmss, Vector3f &desired_vel)
+{
+    Vector2f des_vel_xy(desired_vel.x, desired_vel.y);
+    adjust_velocity(kP, accel_cmss, des_vel_xy);
+    desired_vel.x = des_vel_xy.x;
+    desired_vel.y = des_vel_xy.y;
+}
+
 /*
  * Adjusts the desired velocity for the circular fence.
  */

libraries/AC_Avoidance/AC_Avoid.h

@@ -27,8 +27,10 @@ public:
     /*
      * Adjusts the desired velocity so that the vehicle can stop
      * before the fence/object.
+     * Note: Vector3f version is for convenience and only adjusts x and y axis
      */
     void adjust_velocity(const float kP, const float accel_cmss, Vector2f &desired_vel);
+    void adjust_velocity(const float kP, const float accel_cmss, Vector3f &desired_vel);
 
     static const struct AP_Param::GroupInfo var_info[];