Add option to skip process lookup

[bastjan]

Adds the option netstat.SkipProcessLookup to skip the rather slow PID lookup

[codecov]

Codecov Report

Merging #3 into master will increase coverage by 0.18%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master       #3      +/-   ##
==========================================
+ Coverage   96.66%   96.85%   +0.18%     
==========================================
  Files           4        4              
  Lines         120      127       +7     
==========================================
+ Hits          116      123       +7     
  Misses          2        2              
  Partials        2        2

Impacted Files	Coverage Δ
netstat.go	96.61% <100%> (+0.21%)	⬆️

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