Change axes size.

Here the axes have a size depending on the bone length and not the display.
The latest would imply that the axes would be transfered to the
representation somehow to respond to rendering events. This is an esaier
to implement this.

See Issue #13696

Libs/VTK/Widgets/vtkBoneWidget.cxx

@@ -1323,10 +1323,7 @@ void vtkBoneWidget::RebuildAxes()
     return;
     }
 
-  double distance = 
-   vtkMath::Distance2BetweenPoints(this->WorldHeadRest, this->WorldTailRest)
-     * this->AxesSize; // Rest because distance shouldn't change in pose mode
-                       // anyway
+  double distance = this->GetLength() * this->AxesSize;
   this->AxesActor->SetTotalLength(distance, distance, distance);
 
   vtkSmartPointer<vtkTransform> transform =