Add general Runge-Kutta class - Add a general Runge-Kutta class which time integrates the solution based on coefficients obtained from a Butcher tableau - Add butcher tableau which returns coefficents for the specified Runge-Kutta method - Remove RungKutta4proper, since obsolete

function prof(f)
    profile on
    try
        f();
        profile viewer
    catch e
        fprintf(2, '\n%s', getReport(e));
        profile clear
    end
end