Bug comment: commented out code, weigths don't sum to 1 see #1845
REF: _fit_newton add Ridge correction to Hessian, see also #953
REF: _fit_newton, add ridge_factor option, default 1e-10
REF _fit_newton use np.asarray(hess)
Merge pull request #1847 from josef-pkt/newton_regularize

REF regularize optimize._fit_newton (ridge factor)