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.lower.php

@@ -0,0 +1,31 @@
+<?php
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifierCompiler
+ */
+
+/**
+ * Smarty lower modifier plugin
+ * Type:     modifier<br>
+ * Name:     lower<br>
+ * Purpose:  convert string to lowercase
+ *
+ * @link   http://www.smarty.net/manual/en/language.modifier.lower.php lower (Smarty online manual)
+ * @author Monte Ohrt <monte at ohrt dot com>
+ * @author Uwe Tews
+ *
+ * @param array $params parameters
+ *
+ * @return string with compiled code
+ */
+
+function smarty_modifiercompiler_lower($params)
+{
+    if (Smarty::$_MBSTRING) {
+        return 'mb_strtolower(' . $params[0] . ', \'' . addslashes(Smarty::$_CHARSET) . '\')';
+    }
+    // no MBString fallback
+    return 'strtolower(' . $params[0] . ')';
+}