Use clock package

[hoc081098]

Issue #660.

• Replace DateTime.now() with clock.now().
• Replace Stopwatch with clock.stopwatch().

I don't know if this can cause any breaking changes?

[codecov-commenter]

Codecov Report

Merging #661 (09bb2cf) into master (c5daf4c) will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #661   +/-   ##
=======================================
  Coverage   93.51%   93.51%           
=======================================
  Files          74       74           
  Lines        2281     2281           
=======================================
  Hits         2133     2133           
  Misses        148      148           

[fzyzcjy]

Any updates?