message: Don't create StringRef to temporaries..
diff: @@ -1516,9 +1516,10 @@ void vsnray_writer::write_node(Object obj, std::shared_ptr<sg::node> const& n)
  auto& allocator = document_.GetAllocator();
  + rapidjson::Value name(n->name().c_str(), allocator);
  obj.AddMember(
  rapidjson::StringRef("name"),
  - rapidjson::StringRef(n->name().c_str()),
  + name,
  allocator
  );
  @@ -1773,9 +1774,10 @@ void vsnray_writer::write_data_file(Object obj, data_file::meta_data md, Contain
  allocator
  );
  + rapidjson::Value path(md.path.c_str(), allocator);
  obj.AddMember(
  rapidjson::StringRef("path"),
  - rapidjson::StringRef(md.path.c_str()),
  + path,
  allocator
  );
  @@ -1785,9 +1787,10 @@ void vsnray_writer::write_data_file(Object obj, data_file::meta_data md, Contain
  allocator
  );
  + rapidjson::Value dt(data_type.c_str(), allocator);
  obj.AddMember(
  rapidjson::StringRef("data_type"),
  - rapidjson::StringRef(data_type.c_str()),
  + dt,
  allocator
  );
  