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.noprint.php

@@ -0,0 +1,21 @@
+<?php
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifierCompiler
+ */
+
+/**
+ * Smarty noprint modifier plugin
+ * Type:     modifier<br>
+ * Name:     noprint<br>
+ * Purpose:  return an empty string
+ *
+ * @author   Uwe Tews
+ * @return string with compiled code
+ */
+function smarty_modifiercompiler_noprint()
+{
+    return "''";
+}