Educate `Metric.direction` inference

[HunterMcGushion]

• Metric.direction inference has been extended to look for "error"/"loss" in not only name, but also in the name of metric_function
• This makes it much easier to use short abbreviations like "rmsle" for "root_mean_squared_logarithmic_error" without requiring an explicit direction="min"

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (master@fe581c6). Click here to learn what that means. The diff coverage is 100%.

@@            Coverage Diff            @@
##             master     #167   +/-   ##
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  Coverage          ?   93.88%           
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  Files             ?       46           
  Lines             ?     4939           
  Branches          ?        0           
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  Hits              ?     4637           
  Misses            ?      302           
  Partials          ?        0

Impacted Files	Coverage Δ
hyperparameter_hunter/metrics.py	100% <100%> (ø)

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[coveralls]

Pull Request Test Coverage Report for Build 743

• 10 of 10 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.005%) to 93.885%

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Totals
Change from base Build 741:	0.005%
Covered Lines:	4637
Relevant Lines:	4939

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💛 - Coveralls