With #118, Context::stop_all is moved to Address::stop_all.

Whilst doing this change and updating the docs, I was wondering why we need to provide this functionality within xtra? If the behaviour is the exact same as sending a Stop message to each actor, writing yourself a custom Address::stop_all function is pretty trivial:

struct Actor;
struct Stop;

#[async_trait]
impl Handler<Stop> for Actor {
    type Return = ();

    fn handle(&mut self, _: Stop, ctx: &mut Context<Self>) {
        ctx.stop();
    }
}

// To stop all actors:
address.broadcast(Stop).await;

If we still consider this too much boilerplate, we could provide a xtra-stop-handler crate that offers:

• The Stop message type
• A custom derive #[derive(StopHandler)]

Is there a reason why the implementation of stop_all needs to live xtra? There is a fair bit of code involved in providing it, like a custom envelope etc. We could save a good few lines of code by deleting it if it can really be expressed with existing building blocks.