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
ok i'm fine with that. but if the message were *not* in readable English text then I would consider that as something that somebody might PR in the future, so testing it is valid I think.