Add a weight parameter to construct_zernike_polynomials

[LeeKamentsky]

so that the Zernike of an image can be taken.

[LeeKamentsky]

Duh:

x = construct_zernike_polynomials(..., weights=weights)
y = construct_zernike_polynomials(...) * weights
assert np.all(x == y)

why bother?