Timerit

Added
* Add a succinct module-level `__call__` and `__iter__` API for interactive use
* Add `min_duration` argument

Changed
* Disable REPL printing during profiling

Changed
* Documentation improvements
* Better type stubs

Added
* `robust_times` method
* `summary` method
* relative module

Changed
* Removed Python 2.7, 3.4 and 3.5 support
* Python 3.7+ now uses `perf_counter_ns` by default if available

Added
* Add rankings and consistency properties
* Timerit now remembers results from previous runs

Added
* added `Timerit.reset`
* Timer and Timerit now have class-level default objects and instance specific
instances which can be overwritten for tests / custom purposes.
* Tweaked precision formatting in reports