ENH: I/O of FSL displacements fields

[smoia]

Added FSL displacements

[pull-assistant]

Best reviewed: commit by commit

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Optimal code review plan

     Added FSL Displacement field class and a FSL warp

     Added nonlinear tests for FSL

     corrected inversion of axes and fieldmap creation in fsltest

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[codecov-io]

Codecov Report

Merging #51 into master will decrease coverage by 0.83%.
The diff coverage is 60%.

@@            Coverage Diff             @@
##           master      #51      +/-   ##
==========================================
- Coverage   98.76%   97.92%   -0.84%     
==========================================
  Files          10       10              
  Lines         810      820      +10     
  Branches      106      107       +1     
==========================================
+ Hits          800      803       +3     
- Misses          6       10       +4     
- Partials        4        7       +3

Flag	Coverage Δ
#unittests	97.92% <60%> (-0.84%)	⬇️

Impacted Files	Coverage Δ
nitransforms/io/fsl.py	90.69% <60%> (-4.11%)	⬇️
nitransforms/io/afni.py	96.1% <0%> (-2.6%)	⬇️
nitransforms/base.py	98.8% <0%> (-0.6%)	⬇️
nitransforms/io/itk.py	100% <0%> (ø)	⬆️

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[pep8speaks]

Hello @smoia! Thanks for updating this PR.

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2022-02-16 16:33:44 UTC

[smoia]

All the tests pass, except for test_displacements_field1, parametrised with sw_tool='fsl', image_orientation='LPS', for axis cases 0, 1, (0,1), (1, 2), (0, 1, 2) (but pass for axis=2).

[oesteban]

Note: perhaps some inspiration form fslpy (#99) could help with this one - https://open.win.ox.ac.uk/pages/fsl/fslpy/fsl.transform.nonlinear.html#module-fsl.transform.nonlinear