Controller attribute "counters" is a reserved keyword
This is a real world issue raised by Olivier Ulrich, when he tried to put a CounterController as an attribute inside another controller, and he called it "counters" (
self.counters = myCounterController()).
lscnt() will fail to iterate over counters when you've got a controller with a
counters attribute which is NOT a counter namespace.
When iterating over controllers to look for counters, we should make sure that ctrl.counters is iterable, or that ctrl is a CounterController.