message: Change BoundingBox::addBox so it is more careful about invalid bounding boxes.
diff: @@ -484,10 +484,27 @@ template <typename T, int NDIMS>
  template <typename OtherT>
  AXOM_HOST_DEVICE void BoundingBox<T, NDIMS>::addBox(
  const BoundingBox<OtherT, NDIMS>& bbox)
  +{
  + if(this->isValid())
  + {
  + if(bbox.isValid())
  {
  this->addPoint(bbox.getMin());
  this->addPoint(bbox.getMax());
  }
  + }
  + else
  + {
  + PointType m0, m1;
  + for(int i = 0; i < NDIMS; i++)
  + {
  + m0[i] = static_cast<T>(bbox.getMin()[i]);
  + m1[i] = static_cast<T>(bbox.getMax()[i]);
  + }
  + this->setMin(m0);
  + this->setMax(m1);
  + }
  +}
  //------------------------------------------------------------------------------
  template <typename T, int NDIMS>
  