Draft implementation of RungeKutta with exterior RV updates - Draft class RungeKuttaExteriorRV which updates the residual using a BDF approximation of the derivtive outside of the RK stages. - Draft class for BDF derivative

function names = getVarname(varargin)
    names = cell(size(varargin));

    for i = 1:numel(varargin)
        names{i} = inputname(i);
    end
end