added constants.php file and implemented constants for file system modes
diff --git a/system/codeigniter/CodeIgniter.php b/system/codeigniter/CodeIgniter.php
index 866be35..04936b9 100644
--- a/system/codeigniter/CodeIgniter.php
+++ b/system/codeigniter/CodeIgniter.php
@@ -43,7 +43,14 @@
  * ------------------------------------------------------

  */

 require(BASEPATH.'codeigniter/Compat'.EXT);

-	

+

+/*

+ * ------------------------------------------------------

+ *  Load the compatibility override functions

+ * ------------------------------------------------------

+ */

+require(APPPATH.'config/constants'.EXT);

+

 /*

  * ------------------------------------------------------

  *  Define a custom error handler so we can log PHP errors