AC_Fence: get home distance directly from ahrs

libraries/AC_Fence/AC_Fence.cpp

@@ -241,6 +241,12 @@ bool AC_Fence::check_fence_circle()
         return false;
     }
 
+    Vector2f home;
+    if (_ahrs.get_relative_position_NE_home(home)) {
+        // we (may) remain breached if we can't update home
+        _home_distance = home.length();
+    }
+
     // check if we are outside the fence
     if (_home_distance >= _circle_radius) {
 

libraries/AC_Fence/AC_Fence.h

@@ -95,13 +95,6 @@ public:
     ///     has no effect if no breaches have occurred
     void manual_recovery_start();
 
-    ///
-    /// time saving methods to piggy-back on main code's calculations
-    ///
-
-    /// set_home_distance - update vehicle's distance from home in meters - required for circular horizontal fence monitoring
-    void set_home_distance(float distance) { _home_distance = distance; }
-
     ///
     /// polygon related methods
     ///