Listener socket stream edge receptor

[zippy]

This should have been it's own ticket instead of part of #109, so here are some of it's tasks.

use socket streams and CONVERSE to add a conversation in the _st_new_socket_listener callback, which sends signals on incoming data from the socket and listens for data to send to the socket.

This code needs to also listen on a control aspect for completion commands etc

[zippy]

440cff1 adds CONVERSE based bi-directional socket edge-receptor. Still missing is the control aspect stuff to enable clients to properly close down the socket