message: Simplify `iter` and `iter_mut` in `pane_grid`
diff: @@ -356,12 +356,12 @@ impl<T> State<T> {
  self.panes.get_mut(pane)
  }
  - pub fn iter(&self) -> impl Iterator<Item = (Pane, &T)> {
  - self.panes.iter().map(|(pane, state)| (*pane, state))
  + pub fn iter(&self) -> impl Iterator<Item = (&Pane, &T)> {
  + self.panes.iter()
  }
  - pub fn iter_mut(&mut self) -> impl Iterator<Item = (Pane, &mut T)> {
  - self.panes.iter_mut().map(|(pane, state)| (*pane, state))
  + pub fn iter_mut(&mut self) -> impl Iterator<Item = (&Pane, &mut T)> {
  + self.panes.iter_mut()
  }
  pub fn focused_pane(&self) -> Option<Pane> {
  