Add Serbian language

Signed-off-by: Matt Friedman <maf675@gmail.com>

language/sr/collapsiblecategories.php

@@ -0,0 +1,45 @@
+<?php
+/**
+ *
+ * Collapsible Categories extension for the phpBB Forum Software package.
+ *
+ * @copyright (c) 2015 phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ */
+
+/**
+* DO NOT CHANGE
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+if (empty($lang) || !is_array($lang))
+{
+	$lang = array();
+}
+
+// DEVELOPERS PLEASE NOTE
+//
+// All language files should use UTF-8 as their encoding and the files must not contain a BOM.
+//
+// Placeholders can now contain order information, e.g. instead of
+// 'Page %s of %s' you can (and should) write 'Page %1$s of %2$s', this allows
+// translators to re-order the output of data while ensuring it remains correct
+//
+// You do not need this where single placeholders are used, e.g. 'Message %d' is fine
+// equally where a string contains only two placeholders which are used to wrap text
+// in a url you again do not need to specify an order e.g., 'Click %sHERE%s' is fine
+//
+// Some characters you may want to copy&paste:
+// ’ » “ ” …
+//
+
+$lang = array_merge($lang, array(
+	'COLLAPSIBLE_CATEGORIES_TITLE'	=> array(
+		0 => 'Sakrij kategoriju',
+		1 => 'Prikaži kategoriju',
+	),
+));