Modifying to make callbacks work fine.
Allow concurrent operations.
By default do not call with requests per second.
Do not show an error if there are more requests than asked for.
Keep an array with rounded times.
Improved timing stats to show latency and percentiles.
Make tests run.
Do not show results more than once.
Added test for percentiles, not working.
Percentiles are now working.
Make histogram work well, and percentile test too.
Bumped version number.