Add using statements for ansi-compliance

Nef_2/include/CGAL/Nef_2/Constrained_triang_traits.h

@@ -71,6 +71,19 @@ public:
   typedef typename Base::Halfedge_around_vertex_circulator
           Halfedge_around_vertex_circulator;
 
+
+  using Base::point;
+  using Base::is_isolated;
+  using Base::first_out_edge;
+  using Base::source;
+  using Base::target;
+  using Base::twin;
+  using Base::next;
+  using Base::previous;
+  using Base::cyclic_adj_succ;
+  using Base::cyclic_adj_pred;
+  using Base::delete_vertex;
+
   class lt_edges_in_sweepline : public PMDEC
   {  const Point& p;
      const Halfedge_handle& e_bottom;

Nef_2/include/CGAL/Nef_2/PM_io_parser.h

@@ -74,6 +74,7 @@ class PM_io_parser : public PMDEC
   using Base::source;
   using Base::target;
   using Base::out_edges;
+  using Base::halfedge;
 
   std::istream& in;
   std::ostream& out;

Nef_2/include/CGAL/Nef_2/PM_overlayer.h

@@ -287,6 +287,7 @@ public:
   using Base::source;
   using Base::point;
   using Base::next;
+  using Base::previous;
   using Base::twin;
   using Base::info;
   using Base::link_as_outer_face_cycle;
@@ -299,6 +300,14 @@ public:
   using Base::halfedge;
   using Base::clear_face_cycle_entries;
   using Base::is_closed_at_source;
+  using Base::delete_halfedge_pair;
+  using Base::delete_face;
+  using Base::set_halfedge;
+  using Base::set_hole;
+  using Base::delete_vertex_only;
+  using Base::set_isolated_vertex;
+  using Base::has_outdeg_two;
+  using Base::merge_halfedge_pairs_at_target;
 
   // C++ is really friendly:
   #define USECMARK(t) const Mark& mark(t h) const { return Base::mark(h); }

Nef_2/include/CGAL/Nef_2/PM_point_locator.h

@@ -139,6 +139,19 @@ public:
   using Base::number_of_vertices;
   using Base::number_of_halfedges;
   using Base::number_of_faces;
+  using Base::info;
+  using Base::is_closed_at_source;
+  using Base::source;
+  using Base::target;
+  using Base::cyclic_adj_succ;
+  using Base::mark;
+  using Base::twin;
+  using Base::flip_diagonal;
+  using Base::is_isolated;
+  using Base::first_out_edge;
+  using Base::next;
+  using Base::previous;
+  using Base::face;
 
   Halfedge_const_handle out_wedge(Vertex_const_handle v,
     const Direction& d, bool& collinear) const