Core Auto Updates: Add a initial skin to allow capturing the output from the upgrader without displaying it (such as we need during cron calls).
This has been copied almost verbatim from the automatic-updater plugin with a few style tweaks and additional upgrade-possible check. See #22704

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Update phpdoc for get_current_site(). props jeremyfelt. fixes #25040.
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Add phpdoc for 'wp_redirect' and 'wp_redirect_status' filters. props DrewAPicture. fixes #25215.
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git-svn-id: http://core.svn.wordpress.org/trunk@25200 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Move check_password_reset_key(), reset_password(), and register_new_user() from wp-login.php to wp-includes/user.php, to make them reusable. props beaulebens for initial patch. fixes #20279.
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