MDL-15897: Changed admin_setting_configtext.validate() check to not treat all strings as custom regex's (since PARAM_* constants are now strings).

Instead require them to have '/' at the beginning and end of the pattern.

The only setting that appears to use a custom regex is scorm/apidebugmask - now updated to contain surrounding slashes.

lib/adminlib.php

@@ -1508,7 +1508,8 @@ class admin_setting_configtext extends admin_setting {
      * @return mixed true if ok string if error found
      */
     public function validate($data) {
-        if (is_string($this->paramtype)) {
+        // allow paramtype to be a custom regex if it is the form of /pattern/
+        if (preg_match('#^/.*/$#', $this->paramtype)) {
             if (preg_match($this->paramtype, $data)) {
                 return true;
             } else {