Adding Python 2-compatible type-hints

[apacha]

• Added type-hints to many functions from the code-base.
• Auto-formatted files
• Changed to log.warning instead of log.warn, which is deprecated

[codecov-io]

Codecov Report

Merging #13 into master will increase coverage by 0.08%.
The diff coverage is 25.84%.

@@            Coverage Diff            @@
##           master     #13      +/-   ##
=========================================
+ Coverage    6.67%   6.76%   +0.08%     
=========================================
  Files          12      12              
  Lines        3222    3239      +17     
=========================================
+ Hits          215     219       +4     
- Misses       3007    3020      +13

Impacted Files	Coverage Δ
muscima/cropobject_class.py	0% <0%> (ø)	⬆️
muscima/inference.py	0% <0%> (ø)	⬆️
muscima/graph.py	0% <0%> (ø)	⬆️
muscima/dataset.py	0% <0%> (ø)	⬆️
muscima/io.py	0% <0%> (ø)	⬆️
muscima/grammar.py	0% <0%> (ø)	⬆️
muscima/stafflines.py	0% <0%> (ø)	⬆️
muscima/utils.py	21.66% <25%> (+2.02%)	⬆️
muscima/inference_engine_constants.py	73.84% <50%> (-0.76%)	⬇️
muscima/cropobject.py	24.67% <51.35%> (+0.04%)	⬆️
... and 2 more

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[coveralls]

Pull Request Test Coverage Report for Build 28

• 23 of 89 (25.84%) changed or added relevant lines in 10 files are covered.
• 64 unchanged lines in 7 files lost coverage.
• Overall coverage increased (+0.09%) to 6.761%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
muscima/cropobject_class.py	0	1	0.0%
muscima/dataset.py	0	1	0.0%
muscima/grammar.py	0	1	0.0%
muscima/io.py	0	1	0.0%
muscima/inference_engine_constants.py	2	4	50.0%
muscima/utils.py	2	8	25.0%
muscima/graph.py	0	8	0.0%
muscima/stafflines.py	0	10	0.0%
muscima/cropobject.py	19	37	51.35%
muscima/inference.py	0	18	0.0%

Files with Coverage Reduction	New Missed Lines	%
muscima/utils.py	1	21.67%
muscima/dataset.py	2	0.0%
muscima/io.py	2	0.0%
muscima/stafflines.py	3	0.0%
muscima/inference.py	4	0.0%
muscima/cropobject.py	7	24.68%
muscima/graph.py	45	0.0%

Totals
Change from base Build 26:	0.09%
Covered Lines:	219
Relevant Lines:	3239

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💛 - Coveralls