message: for CGAL 5.2 pre-release to work
diff: @@ -106,7 +106,7 @@ class Alpha_kernel_d<Kernel, true> {
  template<class PointIterator>
  Sphere get_sphere(PointIterator begin, PointIterator end) const {
  // power_center_d_object has been renamed between CGAL 5.1 and 5.2
  -#if CGAL_VERSION_NR < 1050201000
  +#if CGAL_VERSION_NR < 1050200000
  return kernel_.power_center_d_object()(begin, end);
  #else
  return kernel_.construct_power_sphere_d_object()(begin, end);
  @@ -124,7 +124,7 @@ class Alpha_kernel_d<Kernel, true> {
  bool is_gabriel(const Sphere& circumcenter, const Weighted_point_d& point) {
  // power_center_d_object has been renamed between CGAL 5.1 and 5.2
  -#if CGAL_VERSION_NR < 1050201000
  +#if CGAL_VERSION_NR < 1050200000
  return kernel_.power_distance_d_object()(circumcenter, point) >= 0;
  #else
  return kernel_.compute_power_product_d_object()(circumcenter, point) >= 0;
  