Disable RSS feed

There are a lot of user demands to turn off the RSS feed, but there aren't any possibilities to do this in the Drupal 7 (6, 5) admin pages.
http://drupal.org/node/28336

A possible solution:

- modules/system/system.admin.inc
I implemented a checkbox (feed_enabled), to be able to turn off the RSS feed, if the admin wants.
And I implemented a "0" element in the feed_default_tems selection. It is good, if the site owner want RSS feed without real content (the users can subscribe, and the RSS feed may start later).

- includes/common.inc
It can disabled the RSS feed links, if the feed_enabled unchecked.

- modules/node/node.module
It can disabled the RSS page, if the feed_enabled unchecked.