[ENH] Add AFNI's interface to GCOR computation

[oesteban]

This PR adds the wrapper for the @compute_gcor tool.

[codecov-io]

Codecov Report

Merging #2033 into master will increase coverage by <.01%.
The diff coverage is 72.22%.

@@            Coverage Diff             @@
##           master    #2033      +/-   ##
==========================================
+ Coverage   72.19%   72.19%   +<.01%     
==========================================
  Files        1132     1132              
  Lines       57032    57050      +18     
  Branches     8167     8168       +1     
==========================================
+ Hits        41175    41188      +13     
- Misses      14572    14577       +5     
  Partials     1285     1285

Flag	Coverage Δ
#smoketests	72.19% <72.22%> (ø)	⬆️
#unittests	69.79% <72.22%> (ø)	⬆️

Impacted Files	Coverage Δ
nipype/interfaces/afni/__init__.py	100% <ø> (ø)	⬆️
nipype/interfaces/afni/utils.py	76.66% <72.22%> (-0.24%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cda3fdc...5d80df3. Read the comment docs.

[codecov-io]

Codecov Report

Merging #2033 into master will increase coverage by 0.02%.
The diff coverage is 72.22%.

@@            Coverage Diff             @@
##           master    #2033      +/-   ##
==========================================
+ Coverage   72.17%   72.19%   +0.02%     
==========================================
  Files        1136     1132       -4     
  Lines       57147    57050      -97     
  Branches     8185     8168      -17     
==========================================
- Hits        41243    41188      -55     
+ Misses      14617    14577      -40     
+ Partials     1287     1285       -2

Flag	Coverage Δ
#smoketests	72.19% <72.22%> (+0.02%)	⬆️
#unittests	69.79% <72.22%> (+0.01%)	⬆️

Impacted Files	Coverage Δ
nipype/interfaces/afni/__init__.py	100% <ø> (ø)	⬆️
nipype/interfaces/afni/utils.py	76.66% <72.22%> (-0.69%)	⬇️
nipype/scripts/cli.py	39.5% <0%> (-0.98%)	⬇️
nipype/info.py	83.6% <0%> (-0.77%)	⬇️
nipype/interfaces/base.py	83.77% <0%> (-0.03%)	⬇️
...pe/interfaces/spm/tests/test_auto_EstimateModel.py	85.71% <0%> (ø)	⬆️
nipype/workflows/dmri/fsl/epi.py	45.11% <0%> (ø)	⬆️
nipype/interfaces/dipy/__init__.py	100% <0%> (ø)	⬆️
...aces/ants/tests/test_auto_N4BiasFieldCorrection.py	85.71% <0%> (ø)	⬆️
... and 9 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update a61e455...0f1fb6c. Read the comment docs.