Separate max_idle_visitor from max_idle

Cut it to 5 minutes, from max_idle's 15.

Since max_idle now applies only to authenticated players, increasing
it is perfectly safe.

src/lib/player/accept.c

@@ -159,7 +159,8 @@ player_io_deadline(struct player *pl, int write)
 	return 0;
     if (pl->state != PS_PLAYING)
 	return pl->curup + login_grace_time;
-    return pl->curup + minutes(max_idle);
+    return pl->curup
+	+ minutes(pl->nstat & NONVIS ? max_idle: max_idle_visitor);
 }
 
 /*ARGSUSED*/