Refactoring, bugfixes, server responses

- Generalized `send` and `receive` to work on any Binary. This will be
  used in the future to send server responses back to clients.

- FIX: Multiple Asyncs were just waiting for their result immediately,
  capping the number on concurrent forks at 1 in each instance.
- FIX: Potential (?) handle ressource leak in the server loop