Use a byte buffer to reduce number of write calls to stdout

[theckman]

This change introduces a 2KB (growable) byte buffer, to sit in between the painting function(s) and stdout. Previously, as we were animating the spinner we would write the bytes directly to stdout as we were generating the animation.

This change makes it so that most of our writes are to an in-memory buffer, and then we only have one system call to write to the actaul terminal the contents of that buffer.

This should act like a bit of a frame buffer, so if if anyone was experiencing any sort of stutter, where they could see the cursor as the spinner was animated, I believe this should result in a smoother adnimation.

[codecov[bot]]

Codecov Report

Merging #44 (45ccc05) into master (a615053) will decrease coverage by 0.67%. The diff coverage is 55.88%.

:exclamation: Current head 45ccc05 differs from pull request most recent head a339dfc. Consider uploading reports for the commit a339dfc to get more accurate results

@@            Coverage Diff             @@
##           master      #44      +/-   ##
==========================================
- Coverage   94.42%   93.75%   -0.68%     
==========================================
  Files           2        2              
  Lines         520      528       +8     
==========================================
+ Hits          491      495       +4     
- Misses         15       17       +2     
- Partials       14       16       +2     

Flag	Coverage Δ
unittests	93.75% <55.88%> (-0.68%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
spinner.go	93.55% <55.88%> (-0.70%)	:arrow_down:

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[theckman]

When reviewing the report:

Everything is accounted for! No changes detected that need to be reviewed. -- @codecov

Sure, whatever you say...

[theckman]

@codecov is now removed from the project, so the comment above is no longer relevant. Merging!