[TW-1323] Implement Queueing Theory Indicators in burndown reports (Little's Law: TH=WIP/CT)

_Benjamin Weber on 2014-05-13T15:39:40Z says:_

The burndown report shows me:

```
Add rate: 1.1/d Estimated completion: No convergence
Done/Delete rate: 0.8/d
```

```
Add rate: 1.1/d Estimated completion: No convergence
Done/Delete rate: 0.8/d

Life Expectancy of a single task:
Min: 5 mins / Average: 4.43 days / Median: 13.7 days / Max: 90 days

Task added every: 6 days
Task completed every: 7 days
```

Note the numbers are placeholders, only.
Which would be an excellent indicator of the waiting time of any new task entering the waiting line (which task is).

Think of a pond with water:

!Produc2.gif!

Little's Law (cf. attached pdf for a proof):

!ll.png!

The system has a defined limit, its capacity _C_.

Swapped variables:

!ll2.png!

"Cycle time is proportional to queue length."

What is more important to show off?
A. Throughput of all tasks (how much water gets through)
B. Cycle time: time the water stays in the pond
C. Work in progress:

What do _you_ want with burndown?

Criticism requested.

Further Readings:

George, Michael L: The lean six sigma pocket toolbook