Clean up network options.

It's become clear that our network options are insufficient, with the coming
addition of Tor and unix domain support.

Currently:

1. We always bind to local IPv4 and IPv6 sockets, unless --port=0, --offline,
   or any address is specified explicitly.  If they're routable, we announce.
2. --addr is used to announce, but not to control binding.

After this change:

1. --port is deprecated.
2. --addr controls what we bind to and announce.
3. --bind-addr/--announce-addr can be used to control one and not the other.
4. Unless --autolisten=0, we add local IPv4 & IPv6 port 9735 (and announce if they are routable).
5. --offline still overrides listening (though announcing is still the same).

This means we can bind to as many ports/interfaces as we want, and for
special effects we can announce different things (eg. we're sitting
behind a port forward or a proxy).

What remains to implement is semi-automatic binding: we should be able
to say '--addr=0.0.0.0:9999' and have the address resolve at bind
time, or even '--addr=0.0.0.0:0' and have the port autoresolve too
(you could determine what it was from 'lightning-cli getinfo'.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tests/utils.py

@@ -261,7 +261,7 @@ class LightningD(TailableProc):
         opts = {
             'bitcoin-datadir': bitcoin_dir,
             'lightning-dir': lightning_dir,
-            'port': port,
+            'addr': '127.0.0.1:{}'.format(port),
             'allow-deprecated-apis': 'false',
             'override-fee-rates': '15000/7500/1000',
             'network': 'regtest',
@@ -369,7 +369,8 @@ class LightningNode(object):
 
     def start(self):
         self.daemon.start()
-        self.port = self.rpc.getinfo()['port']
+        # This shortcut is sufficient for our simple tests.
+        self.port = self.rpc.getinfo()['address'][0]['port']
 
     def stop(self, timeout=10):
         """ Attempt to do a clean shutdown, but kill if it hangs