Add Croatian (hr) translation

Add complete Croatian translation for Adminer, including all strings
in adminer/lang/hr.inc.php, plural forms support in lang.inc.php,
and Croatian descriptions and translations for all plugins.

plugins/designs.php

@@ -49,5 +49,6 @@ class AdminerDesigns extends Adminer\Plugin {
 		'pl' => array('' => 'Zezwalaj na przełączanie motywów'),
 		'ro' => array('' => 'Permiteți comutarea designurilor'),
 		'ja' => array('' => 'テーマ設定を有効化'),
+		'hr' => array('' => 'Omogućuje promjenu dizajna'),
 	);
 }