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

% Plots all the eigen values for a sparse matrix.
function plotEig(A)
    e = eig(full(A));
    e = sort(e);
    plot(e,'.')
end