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/application/views/errors/error_404.php b/application/views/errors/error_404.php
index fe48fd5..4a8823d 100644
--- a/application/views/errors/error_404.php
+++ b/application/views/errors/error_404.php
@@ -1,4 +1,4 @@
-<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+<?php
 /**
  * CodeIgniter
  *
@@ -24,6 +24,7 @@
  * @since		Version 1.0
  * @filesource
  */
+defined('BASEPATH') OR exit('No direct script access allowed');
 ?><!DOCTYPE html>
 <html lang="en">
 <head>