Made Environment Support optional. Comment out or delete the constant to stop environment checks.
diff --git a/system/helpers/html_helper.php b/system/helpers/html_helper.php
index 53fc899..c6103ab 100644
--- a/system/helpers/html_helper.php
+++ b/system/helpers/html_helper.php
@@ -258,7 +258,7 @@
 
 		if ( ! is_array($_doctypes))
 		{
-			if (is_file(APPPATH.'config/'.ENVIRONMENT.'/doctypes'.EXT))
+			if (defined('ENVIRONMENT') AND is_file(APPPATH.'config/'.ENVIRONMENT.'/doctypes'.EXT))
 			{
 				include(APPPATH.'config/'.ENVIRONMENT.'/doctypes'.EXT);
 			}