Children Drivers

This allows developers to create children drivers that are not prefix
with "CI_". This is a nity grity change, however it keeps with the
mindset that class names that start with CI_ are typically overrides of
core classes.
diff --git a/system/libraries/Driver.php b/system/libraries/Driver.php
index 72f3764..246f47f 100644
--- a/system/libraries/Driver.php
+++ b/system/libraries/Driver.php
@@ -160,9 +160,17 @@
 		// Did we finally find the class?
 		if ( ! class_exists($class_name))
 		{
-			$msg = 'Unable to load the requested driver: '.$class_name;
-			log_message('error', $msg);
-			show_error($msg);
+			// last ditch effort. Maybe someone is coding by the 2.1 driver style.
+			if (class_exists($child_name))
+			{
+				$class_name = $child_name;
+			}
+			else
+			{
+				$msg = 'Unable to load the requested driver: '.$class_name;
+				log_message('error', $msg);
+				show_error($msg);
+			}
 		}
 
 		// Instantiate, decorate and add child