Manually apply PR #1594 (fixing phpdoc page-level generation/warnings)

Also partially fixes issue #1295, fixes inconsistencies in some page-level docblocks and adds include checks in language files.
diff --git a/system/libraries/Session/drivers/Session_native.php b/system/libraries/Session/drivers/Session_native.php
index a837b89..3e700ad 100755
--- a/system/libraries/Session/drivers/Session_native.php
+++ b/system/libraries/Session/drivers/Session_native.php
@@ -1,4 +1,4 @@
-<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+<?php
 /**
  * CodeIgniter
  *
@@ -9,7 +9,7 @@
  * Licensed under the Open Software License version 3.0
  *
  * This source file is subject to the Open Software License (OSL 3.0) that is
- * bundled with this package in the files license.txt / license.rst. It is
+ * bundled with this package in the files license.txt / license.rst.  It is
  * also available through the world wide web at this URL:
  * http://opensource.org/licenses/OSL-3.0
  * If you did not receive a copy of the license and are unable to obtain it
@@ -24,6 +24,7 @@
  * @since		Version 1.0
  * @filesource
  */
+defined('BASEPATH') OR exit('No direct script access allowed');
 
 /**
  * Native PHP session management driver