lightningd: store our id as a struct pubkey as well as struct node_id.

We convert it in various places, so do that only once.  Also, the name
"id" is a little curt.

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

lightningd/lightningd.c

@@ -1416,7 +1416,7 @@ int main(int argc, char *argv[])
 	 * tal_bytelen() to get the length. */
 	log_info(ld->log, "--------------------------------------------------");
 	log_info(ld->log, "Server started with public key %s, alias %s (color #%s) and lightningd %s",
-		 fmt_node_id(tmpctx, &ld->id),
+		 fmt_node_id(tmpctx, &ld->our_nodeid),
 		 json_escape(tmpctx, (const char *)ld->alias)->s,
 		 tal_hex(tmpctx, ld->rgb), version());
 	ld->state = LD_STATE_RUNNING;