We were closing the event QueuedChannel objects in the wrong place;
they should have been closed on test teardown, not on stopBridge
(which was just a test action and wasn't always called).
In order to make the events more scalable, i replace all the
QueuedChannel objects with a single event collector, which would
create QueuedChannels on demand when it receives an event of a new type.
cb04dabea8