issue 7 and 8

[AImager]

• add go mod instead of vendor
• support darwin build

[codecov]

Codecov Report

Merging #9 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master       #9   +/-   ##
=======================================
  Coverage   69.10%   69.10%           
=======================================
  Files           5        5           
  Lines         492      492           
=======================================
  Hits          340      340           
  Misses         94       94           
  Partials       58       58           

Impacted Files	Coverage Δ
mmap_unix.go	72.72% <ø> (ø)

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[sns1988]

LGTM!

[sns1988]

AImager add excemple for go mod， I believe that！