In Curve: Added numerical FD differentiation if derivative is not supplied. Added arc length computation based on the derivative. Added arc length parameterization (but this function is very slow.). In +util: Added fzero_vec.m and integral_vec.m, which call fzero and integral but take vector arguments.

function e = error1d(discr, v1, v2)
    h = discr.h;
    e = sqrt(h*sum((v1-v2).^2));
end