util: introduce timer()...
util: introduce timer()
As documented for timeit.default_timer, there are better timers available for
performance measures on some platforms. These timers don't have a set epoch,
and thus are only useful for interval measurements, but have higher
resolution, and thus get you a better measurement overall.
Use the same selection logic as Python's timeit.default_timer. This is a
platform clock on Python 2 and early Python 3, and time.perf_counter on Python
3.3 and later (where time.perf_counter is introduced as the best timer to use).
