replace time.clock with perf_counter for py3

[frostming]

Replace the timer to suppress the deprecation warning.

[rsyring]

#662 uses if sys.version_info >= (3, 3): while this PR uses sys.version_info[:2] >= (3, 3):. I believe both would work given tuple comparison semantics and the former is just a bit cleaner.

Also, we don't currently have CI setup and I don't have easy access to a Windows machine. Will someone manually confirm that this code works as expected on Windows for Python 2.7 and a version of Python3 > 3.3.

[frostming]

@rsyring I squashed the commits and tested on Windows PC, with Python 3.7.2 and Python 2.7.15, all pass. Thanks

[rsyring]

Great, thank you. I'll update the milestone to 2.4 as I see no reason to delay this.

[rsyring]

Would you mind rebasing this on the current 2.x-maintenance branch and change the PR to merge into that branch? I believe that is the last step needed before I can get this merged.

Thanks.

[davidism]

The command for that would be git rebase --onto origin/2.x-maintenance origin/master deprecate-timer, then git push -f, then edit the PR here to change the target.

@rsyring I usually do this myself, as it's not a common thing for most PR authors to know.

[rsyring]

@davidism ok, I'll take care of it then. Thanks @frostming for the submission.

[rsyring]

@davidism I merged this PR to the maintenance branch, after rebasing again, but the PR didn't pick up that the commit was merged. Let me know here or on Discord if you can tell what I did wrong.

Closing this PR, but it was merged.