Add `EngineerStep` comparison with str

[HunterMcGushion]

• Allow equality testing between EngineerStep and strings of form produced by :meth:EngineerStep.stringify
• Also refactor EngineerStep.__eq__ to utilize EngineerStep.get_comparison_attrs for comparisons against other EngineerStep instances or dicts

[codecov[bot]]

Codecov Report

Merging #158 into master will increase coverage by 0.02%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #158      +/-   ##
==========================================
+ Coverage    93.7%   93.72%   +0.02%     
==========================================
  Files          46       46              
  Lines        4829     4845      +16     
==========================================
+ Hits         4525     4541      +16     
  Misses        304      304

Impacted Files	Coverage Δ
hyperparameter_hunter/feature_engineering.py	100% <100%> (ø)	:arrow_up:

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[coveralls]

Pull Request Test Coverage Report for Build 697

• 21 of 21 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 93.725%

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Totals
Change from base Build 695:	0.02%
Covered Lines:	4541
Relevant Lines:	4845

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💛 - Coveralls