test: remove node::operator<

This method is no longer used.
rfc862c: remove spurious #includes

These were left over from initial development and are unnecessary.
try: throw strerror instead of function name
any_address: construction from sockaddr + socklen_t

This allows construction of an any_address from an existing sockaddr, e.g.
from getaddrinfo, so that it can be used as a socket_address, e.g.  to
construct a connector.
rfc862c: add name resolution

Instead of just connecting to localhost, rfc862c now takes a list of hosts
to try on the command line.  It uses getaddrinfo to do the resolution, which
is not ideal in general but works well enough here.  On a failed connect, it
moves on to the next address and then the next host in the list.

After any successful connect, the process acts as an echo client (as before)
and then exits with EXIT_SUCCESS.  If there is no successful connection, it
exits with EXIT_FAILURE.