Remove py2

[sertansenturk]

• Removed Python 2 support
• Improved setup.py
• Minor linting and code improvements

[codecov]

Codecov Report

Merging #110 into dev will decrease coverage by 0.01%.
The diff coverage is 1.29%.

@@           Coverage Diff            @@
##             dev    #110      +/-   ##
========================================
- Coverage   0.41%   0.39%   -0.02%     
========================================
  Files         46      46              
  Lines       5074    5003      -71     
========================================
- Hits          21      20       -1     
+ Misses      5053    4983      -70

Impacted Files	Coverage Δ
tomato/joint/completeanalyzer.py	0% <ø> (ø)	⬆️
tomato/symbolic/symbtr/dataextractor.py	0% <ø> (ø)	⬆️
tomato/audio/makamtonic/knnclassifier.py	0% <ø> (ø)	⬆️
tomato/symbolic/symbtr/reader/musicxml.py	0% <ø> (ø)	⬆️
tomato/symbolic/symbtranalyzer.py	0% <0%> (ø)	⬆️
tomato/audio/makamtonic/toniclastnote.py	0% <0%> (ø)	⬆️
tomato/audio/pitchfilter.py	0% <0%> (ø)	⬆️
tomato/audio/ahenk.py	0% <0%> (ø)	⬆️
tomato/audio/predominantmelody.py	0% <0%> (ø)	⬆️
tomato/symbolic/symbtr/reader/txt.py	0% <0%> (ø)	⬆️
... and 36 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b925d55...66fcaf5. Read the comment docs.