Fix TimeWindow not resetting buckets when re-using them.

[MathiasGr]

Fixes #13

[codecov]

Codecov Report

Merging #14 (975d3d0) into master (fe8c9d1) will increase coverage by 1.65%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #14      +/-   ##
==========================================
+ Coverage   91.95%   93.60%   +1.65%     
==========================================
  Files           4        4              
  Lines         174      219      +45     
==========================================
+ Hits          160      205      +45     
  Misses          9        9              
  Partials        5        5              

Impacted Files	Coverage Δ
time.go	100.00% <100.00%> (ø)
point.go	100.00% <0.00%> (ø)
window.go	100.00% <0.00%> (ø)
reduce.go	90.66% <0.00%> (+1.95%)	⬆️

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[ensary]

Thank you, @MathiasGr !

[nkhan-atlassian]

looks good to me. Thank you for adding in that bucket reset!