message: new impl of next_iter
diff: @@ -98,11 +98,10 @@ where
  fn next_iter<'a>(
  &mut self,
  op: &mut OpWrapper<'a, O>,
  - cur_param: &O::Param,
  + state: IterState<O::Param, O::Hessian>,
  ) -> Result<ArgminIterData<O::Param>, Error> {
  - // let param = self.cur_param();
  - let grad = op.gradient(cur_param)?;
  - let new_param = cur_param.scaled_sub(&self.omega, &grad);
  + let grad = op.gradient(&state.cur_param)?;
  + let new_param = state.cur_param.scaled_sub(&self.omega, &grad);
  let out = ArgminIterData::new(new_param, 0.0);
  Ok(out)
  }
  