Strings we need to hard code and WP_I18N prefix

[nacin]

Going over some of the MS initialization I've noticed that there are numerous strings we need to provide WP_I18N prefixes to.

Additionally, we use __() in a few spots (at least one) after l10n.php is included, but before we do the locale. We need to hard-code those, and potentially consider moving down the l10n include as far down as possible in wp-settings.php unless there's something in there that we need earlier.

There's a patch at ​http://core.trac.wordpress.org/attachment/ticket/11644/11644.no-i18n.diff, though there's a function_exists('__') in there. This clearly won't work as we will only call this function after l10n.php is included but before the locale is loaded.

I think we also need to cut down on the support message in ms_not_installed(). Currently this is broken as don't have l10n.php included at this point but it does expect it to be.

[nacin]

Maintenance message also in #12485.

[wpmuguru]

[13575] removed the calls from ms_not_installed.

[nbachiyski]

I think I found all MS strings used before the locale is loaded and wrapped them in WP_I18N comments. I also tested with the extraction script and it all looks fine.

[nbachiyski]

(In [13797]) Wrap transtable strings used in Network install in WP_I18N_SOMETHING, because translations still aren't loaded. Fixes #12357