Move $strings from App to Core\L10n

- Add L10n::init() call in App constructor
- Improve pushLang/popLang
- Remove no longer needed references to App

src/Core/Console/Maintenance.php

@@ -68,11 +68,6 @@ HELP;
 			throw new \RuntimeException('Database isn\'t ready or populated yet');
 		}
 
-		Core\Config::load();
-
-		$lang = Core\L10n::getBrowserLanguage();
-		Core\L10n::loadTranslationTable($lang);
-
 		$enabled = intval($this->getArgument(0));
 
 		Core\Config::set('system', 'maintenance', $enabled);