socket in nonblocking mode. An operation that would block now
raises (continuable) a condition of type &i/o-would-block which
contains the port in question. There's no way to handle the
condition gracefully yet.
name (e.g. "www.google.com" and "http") and returns two binary ports:
the first for output and the second for input.
Both ports must be closed for the connection to close.
Also added an example in lab/tcp-connect-example.ss which connects
to an http server, sends "GET /\n" and prints the responde.