Don't include plugin.php twice in setup-config.php.

fixes #28744. see #28740, [28978].

Built from https://develop.svn.wordpress.org/trunk@29005


git-svn-id: http://core.svn.wordpress.org/trunk@28793 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Bring the language chooser to setup-config.php.

see #28577.

Built from https://develop.svn.wordpress.org/trunk@29006


git-svn-id: http://core.svn.wordpress.org/trunk@28794 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Introduce wp_dropdown_languages() and use it on general settings.

Early rough cut. Obviously not fully implemented.

see #15677.

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git-svn-id: http://core.svn.wordpress.org/trunk@28795 1a063a9b-81f0-0310-95a4-ce76da25c4cd