Correct references for solvers.

///     ...

///  }

///  @endcode

///  When a new dispersion function is subclassed from

///  @ref dispersion::dispersion_function no methods need to be overloaded, In

///  stead expressions for

///  * @ref dispersion::dispersion_function::kx_next

///  * @ref dispersion::dispersion_function::ky_next

///  * @ref dispersion::dispersion_function::kz_next

///  * @ref dispersion::dispersion_function::x_next

///  * @ref dispersion::dispersion_function::y_next

///  * @ref dispersion::dispersion_function::z_next

///  * @ref dispersion::dispersion_function::t_next

///  When a new solver method is subclassed from

///  @ref solver::solver_interface no methods need to be overloaded, Instead

///  expressions for

///  * @ref solver::solver_interface::kx_next

///  * @ref solver::solver_interface::ky_next

///  * @ref solver::solver_interface::kz_next

///  * @ref solver::solver_interface::x_next

///  * @ref solver::solver_interface::y_next

///  * @ref solver::solver_interface::z_next

///  * @ref solver::solver_interface::t_next

///

///  must be created.

//------------------------------------------------------------------------------

#ifndef solver_h

#define solver_h