Update Language\L10n class and drop all legacy code

new Langauge\GetLocale::setLocale() for getting new type lang info from
session, etc
L10n class call chnage of parameters:
NEW: locale, domain, path
OLD: locale, path, domain, legacy(bool)

Temporary auto detect for possible path/domain switch if domain value
has slash inside

Rename all local files to names matching locale folder
en_US -> en

Delete lang folders with symlinks as they are no longer used

Update all header files and class Backend\Admin, ACL\Login,
Output\Form\Generate, Template\SmartyExtend with new language order:
call ::setLocale() afer login class

Update missing test translation strings in all po files

Update phpUnit tests to match all new changes

www/includes/admin_header.php

@@ -72,10 +72,19 @@ if (
 $db = new CoreLibs\DB\IO(DB_CONFIG, $log);
 // login & page access check
 $login = new CoreLibs\ACL\Login($db, $log);
+// lang, path, domain
+// pre auto detect language after login
+$locale = \CoreLibs\Language\GetLocale::setLocale();
+// set lang and pass to smarty/backend
+$l10n = new \CoreLibs\Language\L10n(
+	$locale['locale'],
+	$locale['domain'],
+	$locale['path'],
+);
 // create smarty object
-$smarty = new CoreLibs\Template\SmartyExtend();
+$smarty = new CoreLibs\Template\SmartyExtend($l10n, $locale);
 // create new Backend class with db and loger attached
-$cms = new CoreLibs\Admin\Backend($db, $log);
+$cms = new CoreLibs\Admin\Backend($db, $log, $l10n, $locale);
 // the menu show flag (what menu to show)
 $cms->menu_show_flag = 'main';
 // db info