daemon: batching of changes as per BOLT #2.

We now keep a list of commitment transaction states for "us" and
"them", as well as a "struct channel_state" for staged changes.

We manipulate these structures as we send out packets, receive
packets, or receive acknowledgement of packets.  In particular, we
update the other nodes' staging_cstate as we send out our requests,
and update our own staging_cstate are we receive acks.  When we
receive a request, we update both (as we immediately send out our
ack).

The RPC output is changed; rather than expose the complexity, we
expose our last committed state: what would happen if we have to drop
to the blockchain now.

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

daemon/jsonrpc.c

@@ -252,6 +252,7 @@ static const struct json_command *cmdlist[] = {
 	&newhtlc_command,
 	&fulfillhtlc_command,
 	&failhtlc_command,
+	&commit_command,
 	&close_command,
 	/* Developer/debugging options. */
 	&echo_command,