improve initialization when features are inserted

when the c3t3 contains no cells after initialization by features,
it may be needed to add more points for initialization, even when
the nb of facets in complex is > 0
It is the case for example when facets cover a very small part, or
too few connected components of the domain

Mesh_3/include/CGAL/Mesh_3/C3T3_helpers.h

@@ -792,6 +792,7 @@ public:
                                    Moving_vertices_set& moving_vertices);
 
   void update_restricted_facets();
+  void update_restricted_cells();
 
 #ifdef CGAL_INTRUSIVE_LIST
   template <typename OutdatedCells>
@@ -2925,6 +2926,18 @@ update_restricted_facets()
     updater(*fit);
 }
 
+template <typename C3T3, typename MD>
+void
+C3T3_helpers<C3T3, MD>::
+update_restricted_cells()
+{
+  Update_c3t3 updater(domain_, c3t3_);
+  for (typename C3T3::Triangulation::Finite_cells_iterator
+    cit = tr_.finite_cells_begin();
+    cit != tr_.finite_cells_end(); ++cit)
+    updater(cit);
+}
+
 template <typename C3T3, typename MD>
 template <typename OutdatedCellsOutputIterator,
           typename DeletedCellsOutputIterator>

Mesh_3/include/CGAL/make_mesh_3.h

@@ -326,6 +326,13 @@ struct C3t3_initializer < C3T3, MD, MC, true, CGAL::Tag_true >
         if (c3t3.number_of_facets() == 0) {
           need_more_init = true;
         }
+        else
+        {
+          helper.update_restricted_cells();
+          if(c3t3.number_of_cells() == 0) {
+            need_more_init = true;
+          }
+        }
       }
       if(need_more_init) {
         init_c3t3(c3t3, domain, criteria,