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 A = kr(varargin)
    n = nargin;

    A = 1;

    for i = 1:n
        A = kron(A,varargin{i});
    end
end