message: Pass mesh as const& in write*obj to avoid unnecessary copy
diff: @@ -40,7 +40,7 @@ namespace core {
  * @param[in] mesh The mesh to save as obj.
  * @param[in] filename Output filename (including ".obj").
  */
  -inline void write_obj(Mesh mesh, std::string filename)
  +inline void write_obj(const Mesh& mesh, std::string filename)
  {
  assert(mesh.vertices.size() == mesh.colors.size() || mesh.colors.empty());
  assert(mesh.tvi.size() == mesh.tti.size() || mesh.tti.empty());
  @@ -112,7 +112,7 @@ inline void write_obj(Mesh mesh, std::string filename)
  * @param[in] mesh The mesh to save as obj.
  * @param[in] filename Output filename, including .obj.
  */
  -inline void write_textured_obj(Mesh mesh, std::string filename)
  +inline void write_textured_obj(const Mesh& mesh, std::string filename)
  {
  assert(mesh.vertices.size() == mesh.colors.size() || mesh.colors.empty());
  assert(!mesh.texcoords.empty());
  