title: Create and call actor from another actor in actix
body: <p>I am using <code>actix</code> to implement some simple processing logic in rust. The idea is that I have an actor type <code>Parent</code> which makes some decision and sometimes needs to create a <code>Child</code> actor, send message to it and get response. I noticed that <code>actix</code> <code>Handler</code> cannot be <code>async</code> therefore not allowing me to create an actor and receive response from it.</p>
  <p>Is there a way to call an actor from another actor in <code>actix</code>?</p>