message: Implement `Overlay::translate`
diff: -use crate::{layout, Clipboard, Event, Hasher, Layer, Layout, Point, Size};
  +use crate::{
  + layout, Clipboard, Event, Hasher, Layer, Layout, Point, Size, Vector,
  +};
  use std::rc::Rc;
  #[allow(missing_debug_implementations)]
  @@ -18,6 +20,11 @@ where
  Self { position, layer }
  }
  + pub fn translate(mut self, translation: Vector) -> Self {
  + self.position = self.position + translation;
  + self
  + }
  +
  pub fn map<B>(self, f: Rc<dyn Fn(Message) -> B>) -> Overlay<'a, B, Renderer>
  where
  Message: 'static,
  