Add MLSMOTE algorithm to imblearn

[balvisio]

What does this implement/fix? Explain your changes.

This is an implementation of the Multilabel SMOTE (MLSMOTE) algorithm described in the paper:

Charte, F. & Rivera Rivas, Antonio & Del Jesus, María José & Herrera, Francisco. (2015). MLSMOTE: Approaching imbalanced multilabel learning through synthetic instance generation. Knowledge-Based Systems. -. 10.1016/j.knosys.2015.07.019.

It is an oversampling technique that AFAIK there is no open-source implementation yet.

Addresses: #340

Any other comments?

The implementation is ready to be reviewed. Once reviewed, I can squash the commits for cleaner history.

[codecov]

Codecov Report

Attention: Patch coverage is 95.11111% with 11 lines in your changes missing coverage. Please review.

Project coverage is 93.33%. Comparing base (6176807) to head (70e1f96).
Report is 98 commits behind head on master.

Files with missing lines	Patch %	Lines
imblearn/over_sampling/_mlsmote.py	92.25%	6 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #927      +/-   ##
==========================================
- Coverage   97.19%   93.33%   -3.87%     
==========================================
  Files          97       96       -1     
  Lines        6348     6422      +74     
  Branches      711      582     -129     
==========================================
- Hits         6170     5994     -176     
- Misses        106      363     +257     
+ Partials       72       65       -7     

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[rjurney]

@balvisio Thank you! You are a scholar and a gentleman.

[balvisio]

thank you @rjurney , my pleasure. Looking forward to any feedback.

[h-holm]

Thanks for the great work, @balvisio! Do we have any news on this PR?

[balvisio]

Hello @h-holm , thank you. I am waiting for the maintainers to review the code so that the PR can be merged.

[h-holm]

Thanks for the update, @balvisio. Crossing my fingers that @glemaitre and others can chip in when time allows, as this would be a great addition 🤞

[enewhuis]

Is this just waiting on fixing the test coverage? ....and rebase?