BUG emplike `emplikeAFT.predict` uses endog

I don't think this can be right

    def predict(self, params, endog=None):
        if endog is None:
            endog = self.endog
        return np.dot(endog, params)

The results class doesn't define predict and doesn't inherit, so I guess it has never been used.

separation between the model class emplikeAFT and the results class AFTResults looks strange.
fitting is params of the results class.

Start at the emplikeAFT.predict method shown in the issue and inspect how emplikeAFT and AFTResults are separated and how fitting supplies parameters. Determine which class should expose prediction and which input it should use; the issue is done when prediction behavior and the model/results boundary are made consistent.