0.4.0-alpha.9

• Added 'project_into' method to #[pin_project] types. This can be useful when returning a pin projection from a method.

  fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T> {
      self.project_into().pinned
  }

• Prevented UnpinStruct from appearing in the document by default. See taiki-e/pin-project#71 for more details.