Slow consumers not disconnected if producer msg/s rate is low

There is still a problem how producer msg/s rate is calculated in QueueImpl.getRate() for slow consumer detection. It calculates only messages added during the last slow consumer check period. As this is used to figure out, in which msg/s rate the queue could serve the consumer then it should also take into account messages which are already in queue at the start of queueRateCheckTime period.

Current implementation is problem for cases when messages are sent to queue in bursts, for example producer sends 1000s messages in a few seconds and then stops and will do that again in 1 hour. QueueImpl.getRate() method returns 0 msg/s for slow consumer check period set to for example 5 min and slow consumer detection will be skipped.