Introduces Textpattern_L10n_Locale::getLocaleIdentifiers().

Allows getting locale identifiers for the specified language.
May prove useful for multilingual (plugins) and language
detection.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5629 2fea6a4d-a838-0410-917b-93a53c48e9d2
Return FALSE on failure.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5630 2fea6a4d-a838-0410-917b-93a53c48e9d2
Missing strtolower().

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5631 2fea6a4d-a838-0410-917b-93a53c48e9d2