Since WPLANG is deprecated in Wordpress 4, what do you use to set a user selected language? In versions 3.x.x I used define('WPLANG', $lang) to set a language and then on the pages could get it using get_locale(). I need to use this approach to differentiate the content for the different languages. I know that it's possible to change the language in Settings->General but I need to do that programmatically.
Thanks