Allow for the residual normalization function to return a vector. Also change the default normalization from normalizing on norm(u-mean(u),inf) to norm(u/2), since this proved to be better for 1d burgers

function q = convergence(e,h)
    for i = 1:length(e)-1
        q(i) = log(e(i)/e(i+1))/log(h(i+1)/h(i));
    end
end