Add 'bold' and 'dti' contrast type to bbregister

[chrisgorgo]

No description provided.

[codecov-io]

Codecov Report

Merging #1929 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1929      +/-   ##
==========================================
- Coverage   72.55%   72.54%   -0.01%     
==========================================
  Files        1064     1064              
  Lines       54180    54178       -2     
  Branches     7811     7811              
==========================================
- Hits        39308    39306       -2     
  Misses      13654    13654              
  Partials     1218     1218

Flag	Coverage Δ
#smoketests	72.54% <100%> (-0.01%)	⬇️
#unittests	70.01% <100%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
nipype/interfaces/freesurfer/preprocess.py	66.7% <100%> (-0.08%)	⬇️
...ype/interfaces/freesurfer/tests/test_BBRegister.py	77.77% <0%> (ø)	⬆️

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[effigies]

$ bbregister --help
[...]
	Contrast Arguments (one required)
	--t1
		Assume t1 contrast, ie, White Matter brighter than Grey Matter
	--t2
		Assume t2 contrast, ie, Gray Matter brighter than White Matter
	--bold
		Same as --t2
	--dti
		Same as --t2

If we're going to add bold, I figure we should add dti; but is there any particular reason to add aliases?

[chrisgorgo]

You are right it is an alias. I've added 'dti'. It does not hurt to have those and it makes easier for new nipype users accustomed to certain flags.