Makes a safe copy of the model.

def copy(self):
        """
        Makes a safe copy of the model.
        """
        copied_model = GPModel(kernel = self.model.kern.copy(),
                            noise_var=self.noise_var,
                            exact_feval=self.exact_feval,
                            optimizer=self.optimizer,
                            max_iters=self.max_iters,
                            optimize_restarts=self.optimize_restarts,
                            verbose=self.verbose,
                            ARD=self.ARD)

        copied_model._create_model(self.model.X,self.model.Y)
        copied_model.updateModel(self.model.X,self.model.Y, None, None)
        return copied_model