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/language/english/db_lang.php b/system/language/english/db_lang.php
index 479cbb1..180bd4a 100644
--- a/system/language/english/db_lang.php
+++ b/system/language/english/db_lang.php
@@ -24,6 +24,7 @@
  * @since		Version 1.0
  * @filesource
  */
+defined('BASEPATH') OR exit('No direct script access allowed');
 
 $lang['db_invalid_connection_str'] = 'Unable to determine the database settings based on the connection string you submitted.';
 $lang['db_unable_to_connect'] = 'Unable to connect to your database server using the provided settings.';