Update Smarty to 3.1.21

- add missing block.tphp, block.textformat.php, function.popup.php,
  function.popup_init.php
- update function in function.html_checkboxes.php,
  function.html_options.php

www/Smarty-3.1.21/plugins/modifiercompiler.cat.php

@@ -0,0 +1,29 @@
+<?php
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifierCompiler
+ */
+
+/**
+ * Smarty cat modifier plugin
+ * Type:     modifier<br>
+ * Name:     cat<br>
+ * Date:     Feb 24, 2003<br>
+ * Purpose:  catenate a value to a variable<br>
+ * Input:    string to catenate<br>
+ * Example:  {$var|cat:"foo"}
+ *
+ * @link     http://smarty.php.net/manual/en/language.modifier.cat.php cat
+ *           (Smarty online manual)
+ * @author   Uwe Tews
+ *
+ * @param array $params parameters
+ *
+ * @return string with compiled code
+ */
+function smarty_modifiercompiler_cat($params)
+{
+    return '(' . implode(').(', $params) . ')';
+}