Revert "Remove 'reg_term'/'regularisation' from dwi2tensor interface"

This reverts commit 6dabc88.

Author: ihnorton

nipype/interfaces/mrtrix3/reconst.py

@@ -38,6 +38,12 @@ class FitTensorInputSpec(MRTrix3BaseInputSpec):
         'rician',
         argstr='-method %s',
         desc=('select method used to perform the fitting'))
+    reg_term = traits.Float(
+        5.e3, usedefault=True,
+        argstr='-regularisation %f',
+        desc=('specify the strength of the regularisation term on the '
+              'magnitude of the tensor elements (default = 5000). This '
+              'only applies to the non-linear methods'))
 
 
 class FitTensorOutputSpec(TraitedSpec):
@@ -58,7 +64,8 @@ class FitTensor(MRTrix3Base):
     >>> tsr.inputs.in_mask = 'mask.nii.gz'
     >>> tsr.inputs.grad_fsl = ('bvecs', 'bvals')
     >>> tsr.cmdline                               # doctest: +ELLIPSIS
-    'dwi2tensor -fslgrad bvecs bvals -mask mask.nii.gz dwi.mif dti.mif'
+    'dwi2tensor -fslgrad bvecs bvals -mask mask.nii.gz \
+-regularisation 5000.000000 dwi.mif dti.mif'
     >>> tsr.run()                                 # doctest: +SKIP
     """