Adding geomin to rotations

[jbiggsets]

This is a PR to add orthogonal and oblique geomin rotations to factor_analyzer's Rotator() class. It includes several tests to ensure that the output matches what we get from R's fa() function in psych (which relies on the GPArotation library).

The main change is adding a new objective _geomin_obj(). This should address #63 .

[codecov]

Codecov Report

Merging #64 into master will increase coverage by 0.58%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #64      +/-   ##
==========================================
+ Coverage   94.53%   95.11%   +0.58%     
==========================================
  Files           5        6       +1     
  Lines         824      963     +139     
==========================================
+ Hits          779      916     +137     
- Misses         45       47       +2     

Impacted Files	Coverage Δ
factor_analyzer/test_utils.py	98.41% <ø> (ø)
factor_analyzer/rotator.py	95.60% <100.00%> (+0.29%)	⬆️

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[zeromh]

LGTM!

[zeromh]

@jbiggsets, just wondering if you have an estimate on when PR will be merged? Also are you planning a new release at some point?

[zeromh]

@jbiggsets @desilinguist ?
Do you have some idea of when this will be added?