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

% Prints the version and location of the sbplib currently in use.
function sbplibVersion()
    location = sbplibLocation();

    name = 'sbplib (feature/grids)';
    ver = '0.0.x';

    fprintf('%s %s\n', name, ver);
    fprintf('Running in:\n%s\n', location);
end