/// \brief Read a map graph into \p root from \p outputStream, using \p entityTable to create entities.
virtual void readGraph( scene::Node& root, TextInputStream& inputStream, EntityCreator& entityTable ) const = 0;
/// \brief Write the map graph obtained by applying \p traverse to \p root into \p outputStream.
/// \brief Read a map graph into \p root from \p outputStream, using \p entityTable to create entities.
virtual void readGraph( scene::Node& root, TextInputStream& inputStream, EntityCreator& entityTable ) const = 0;
/// \brief Write the map graph obtained by applying \p traverse to \p root into \p outputStream.