feat: Base64 and Base64Url encoding schemes

[rafamizes]

Closes #12

[codecov]

Codecov Report

Merging #13 (ac6dace) into master (c083a36) will increase coverage by 27.35%.
The diff coverage is 98.57%.

@@             Coverage Diff             @@
##           master      #13       +/-   ##
===========================================
+ Coverage   62.96%   90.32%   +27.35%     
===========================================
  Files           3        5        +2     
  Lines          27       93       +66     
===========================================
+ Hits           17       84       +67     
+ Misses         10        9        -1     

Impacted Files	Coverage Δ
lib/src/rand.dart	100.00% <ø> (ø)
lib/src/bytes.dart	80.00% <80.00%> (ø)
lib/src/base64/base64.dart	100.00% <100.00%> (ø)
lib/src/future_wrap.dart	27.27% <100.00%> (+2.27%)	⬆️
lib/src/text.dart	100.00% <100.00%> (+50.00%)	⬆️

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[dartoosdev]

Everything is ok.

[dartoosdev]

@rultor merge it.

[rultor]

@rultor merge it.

@dartoosdev Thanks for your request. @rafamizes Please confirm this.

[rafamizes]

@rultor merge it.

[rultor]

@rultor merge it.

@rafamizes OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor merge it.

@rafamizes Done! FYI, the full log is here (took me 2min)