Fixed Inheritiance bug and Circular Reference Exception

* When using multiple `extends` in PHP, the order was wrong
* The circular reference path was incorrect when mixing PHP's `extend` and mapping extends, made the exception message less verbose.

Fixes https://github.com/symfony-cmf/RoutingAutoBundle/issues/90
Its nice also to partially match the exception message to be sure (more or less) that the message is displayed:

````
@expectedExceptionMessage Circular reference
````