create_featreg_preproc: reference run modification

[oliver-contier]

ENH

Added possibility to specify which functional run the reference volume should be picked from to the function 'create_featreg_preproc'. The reference run can be selected by integer indexing or with a string ('first', 'middle', 'last') similar to how the reference volume is selected. Also added simple test functions respectively.

We ran an analysis with these changes on nipype version 0.11.0 and it worked fine.

[codecov-io]

Codecov Report

Merging #2190 into master will increase coverage by 0.02%.
The diff coverage is 86.66%.

@@            Coverage Diff             @@
##           master    #2190      +/-   ##
==========================================
+ Coverage   72.28%   72.31%   +0.02%     
==========================================
  Files        1171     1172       +1     
  Lines       58622    58646      +24     
  Branches     8433     8436       +3     
==========================================
+ Hits        42377    42407      +30     
+ Misses      14887    14884       -3     
+ Partials     1358     1355       -3

Flag	Coverage Δ
#smoketests	72.31% <86.66%> (+0.02%)	⬆️
#unittests	69.98% <86.66%> (+0.02%)	⬆️

Impacted Files	Coverage Δ
nipype/workflows/fmri/fsl/tests/test_preprocess.py	100% <100%> (ø)
nipype/workflows/fmri/fsl/preprocess.py	87.15% <73.33%> (-0.82%)	⬇️
nipype/interfaces/base.py	82.94% <0%> (-0.37%)	⬇️
nipype/pipeline/engine/workflows.py	78.75% <0%> (+2.36%)	⬆️

---

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[codecov-io]

Codecov Report

Merging #2190 into master will increase coverage by 0.02%.
The diff coverage is 83.87%.

@@            Coverage Diff             @@
##           master    #2190      +/-   ##
==========================================
+ Coverage   72.28%   72.31%   +0.02%     
==========================================
  Files        1171     1172       +1     
  Lines       58622    58647      +25     
  Branches     8433     8437       +4     
==========================================
+ Hits        42377    42411      +34     
+ Misses      14887    14881       -6     
+ Partials     1358     1355       -3

Flag	Coverage Δ
#smoketests	72.31% <83.87%> (+0.02%)	⬆️
#unittests	69.98% <83.87%> (+0.02%)	⬆️

Impacted Files	Coverage Δ
nipype/workflows/fmri/fsl/tests/test_preprocess.py	100% <100%> (ø)
nipype/workflows/fmri/fsl/preprocess.py	86.9% <68.75%> (-1.06%)	⬇️
nipype/pipeline/engine/workflows.py	78.75% <0%> (+2.36%)	⬆️

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4a0bd3d...64fe757. Read the comment docs.

[satra]

perhaps this if clause should be at the beginning to account for the potential that files is not a list, but a single filename.

[oliver-contier]

Thanks for the remark, changes coming up

[oliver-contier]

Should now also work in case a single file (i.e. functional run) is given.