getinfo: new RPC command

Useful for getting ID, what port (if not set in config file).

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

daemon/lightningd.h

@@ -72,6 +72,9 @@ struct lightningd_state {
 	char *config_dir;
 	char *rpc_filename;
 
+	/* Port we're listening on */
+	u16 portnum;
+	
 	/* Configuration settings. */
 	struct config config;