Reserve hashtable size in K3_tree/SNC_k3_tree_traits

Nef_3/include/CGAL/Nef_3/K3_tree.h

@@ -606,6 +606,7 @@ Node_handle build_kdtree(Vertex_list& V, Halfedge_list& E, Halffacet_list& F,
 #else
   Side_of_plane sop(point_on_plane, coord);
 #endif
+  sop.reserve(V.size());
 
   Vertex_list V1,V2;
   classify_objects(V, sop, V1, V2);

Nef_3/include/CGAL/Nef_3/SNC_k3_tree_traits.h

@@ -85,7 +85,7 @@ public:
 #else
   Side_of_plane(const Point_3& p, int c) : OnSideMap(unknown_side), coord(c), pop(p) {}
 #endif
-
+  void reserve(std::size_t n) { OnSideMap.reserve(n); }
   Oriented_side operator()(Vertex_handle v);
   Oriented_side operator()(Halfedge_handle e);
   Oriented_side operator()(Halffacet_handle f);