fix the argsort that caused inconsistent results due to machine precision errors

[anilyil]

Purpose

This PR addresses #89. The underlying cause was an argsort flipping the order of some entries due to the differences on the order of machine precision. By rounding the array to 8 significant figures before the sorting algorithm, we prevent this behavior.

This might cause some existing runscripts to get a different ordering but as we saw with the test case that started failing, this means that these runscripts were susceptible to this issue anyways. If it shows up, this change will show up as a shuffled ordering of the FFD control points in shape variables.

Type of change

• [x] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (non-backwards-compatible fix or feature)
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no API changes)
• [ ] Documentation update
• [ ] Maintenance update
• [ ] Other (please describe)

Testing

We'll see what azure says

Checklist

• [ ] I have run flake8 and black to make sure the code adheres to PEP-8 and is consistently formatted
• [ ] I have run unit and regression tests which pass locally with my changes
• [ ] I have added new tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation

[codecov[bot]]

Codecov Report

Merging #114 (f6a8fb4) into master (1344987) will decrease coverage by 1.09%. The diff coverage is 100.00%.

:exclamation: Current head f6a8fb4 differs from pull request most recent head 5c2b7de. Consider uploading reports for the commit 5c2b7de to get more accurate results

@@            Coverage Diff             @@
##           master     #114      +/-   ##
==========================================
- Coverage   60.43%   59.34%   -1.10%     
==========================================
  Files          40       40              
  Lines        9671     9669       -2     
==========================================
- Hits         5845     5738     -107     
- Misses       3826     3931     +105     

Impacted Files	Coverage Δ
pygeo/geo_utils/remove_duplicates.py	76.63% <100.00%> (-0.22%)	:arrow_down:
pygeo/constraints/areaConstraint.py	51.63% <0.00%> (-24.84%)	:arrow_down:
pygeo/constraints/DVCon.py	63.97% <0.00%> (-3.24%)	:arrow_down:
pygeo/parameterization/DVGeo.py	65.67% <0.00%> (-0.36%)	:arrow_down:
pygeo/geo_utils/file_io.py	65.78% <0.00%> (-0.23%)	:arrow_down:

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