message: Remove Clone bound on Application::Message
diff: @@ -83,7 +83,7 @@ pub trait Application: Sized {
  /// The type of __messages__ your [`Application`] will produce.
  ///
  /// [`Application`]: trait.Application.html
  - type Message: std::fmt::Debug + Send + Clone;
  + type Message: std::fmt::Debug + Send;
  /// Initializes the [`Application`].
  ///
  