Add runtime refinement option to RuntimeSettings and fix get coordinates inline documentation

   * This is a specialized function to access the X coordinate of a sphere through

   * its index.

   *

   * \param index: `int` Index of the scale to be retrieved.

   * \param index: `int` Index of the sphere (0-based).

   * \return scale: `double` The X coordinate of the requested sphere.

   */

  double get_sph_x(int index) { return _sph_x[index]; }

   * This is a specialized function to access the Y coordinate of a sphere through

   * its index.

   *

   * \param index: `int` Index of the scale to be retrieved.

   * \param index: `int` Index of the sphere (0-based).

   * \return scale: `double` The Y coordinate of the requested sphere.

   */

  double get_sph_y(int index) { return _sph_y[index]; }

   * This is a specialized function to access the Z coordinate of a sphere through

   * its index.

   *

   * \param index: `int` Index of the scale to be retrieved.

   * \param index: `int` Index of the sphere (0-based).

   * \return scale: `double` The Z coordinate of the requested sphere.

   */

  double get_sph_z(int index) { return _sph_z[index]; }

  double _gpu_ram_gb;

  //! \brief Host system memory in GiB.

  double _host_ram_gb;

  //! \brief Refinement flag.

  bool _use_refinement;

public:

  //! \brief Flag for LU factorization inversion.

  const double& gpu_ram_gb = _gpu_ram_gb;

  //! \brief Read-only view on host system memory in GiB.

  const double& host_ram_gb = _host_ram_gb;

  //! \brief Read-only view on refinement flag.

  const bool& use_refinement = _use_refinement;

  /**

   * \brief RuntimeSettings instance constructor.