111.06.00

- Added `?on_wouldblock:(unit -> unit)` callback to
  `Udp.recvmmsg_loop` and `recvmmsg_no_sources_loop`.
- For functions that create `Rpc` connections, added optional
  arguments: `?max_message_size:int` and
  `?handshake_timeout:Time.Span.t`.

  These arguments were already available to `Connection.create`, but
  are now uniformly available to all functions that create
  connections.