message: Move GeogramMesh::ref_vertex to private section
diff: @@ -101,16 +101,17 @@ namespace RINGMesh {
  double* vertex_ptr = mesh_->vertices.point_ptr( v_id ); \
  return *( vecn< DIMENSION >* )( vertex_ptr ); \
  } \
  + virtual index_t nb_vertices() const override \
  + { \
  + return mesh_->vertices.nb(); \
  + } \
  + private: \
  vecn< DIMENSION >& ref_vertex( index_t v_id ) \
  { \
  ringmesh_assert( v_id < nb_vertices() ); \
  double* vertex_ptr = mesh_->vertices.point_ptr( v_id ); \
  return *( vecn< DIMENSION >* )( vertex_ptr ); \
  } \
  - virtual index_t nb_vertices() const override \
  - { \
  - return mesh_->vertices.nb(); \
  - } \
  protected: \
  std::unique_ptr< GEO::Mesh > mesh_
  