MDL-21249 improved php docs and adding direct access prevention in core libs

lib/graphlib.php

@@ -21,10 +21,13 @@
  *
  * Copy of GNU Lesser General Public License at: http://www.gnu.org/copyleft/lesser.txt
  * Contact author at: [email protected]
- * 
- * @package moodlecore
+ *
+ * @package    core
+ * @subpackage lib
  */
 
+defined('MOODLE_INTERNAL') || die();
+
 /* This file contains modifications by Martin Dougiamas
  * as part of Moodle (http://moodle.com).  Modified lines
  * are marked with "Moodle".
@@ -983,7 +986,7 @@ class graph {
       $axis_colour     = $this->parameter['axis_colour'];
       $axis_angle      = $this->parameter['y_axis_angle'];
       $y_tick_labels   = $this->y_tick_labels;
-      
+
       $this->calculated['y_axis_left']['has_data'] = FALSE;
       $this->calculated['y_axis_right']['has_data'] = FALSE;