Add an optional `count` parameter [Feature Request]

[furechan]

Hi,

It would be nice to have an optional count parameter. Sometimes, you want to time a group of similar operations and have an indication of the average time for each item.

The syntax would look like:

with timer("batch", count=10):
    ...

The timer should then display something like:

DEBUG:timer.batch: total 0.10 s / 0.01 s per item (count=10)

Thank You!