ENH: Beef-up LTA tests with one equivalent to mri_concatenate_lta

This PR adds more LTA and corresponding ITK conversions. The ITK
conversions have been calculated with ``lta_convert``. The original
NIfTI files have also been added to this PR for the implementation of
future tests.

Files have been named with some sort of BIDS derived nomenclature. Some
provenance has been recorded as initial comments of the LTA files.

Author: oesteban

nitransforms/tests/data/regressions/T1w_fsnative.nii.gz

@@ -0,0 +1,30 @@
+# This file was generated with bbregister, with fMRIPrep-20.0.5's settings
+type      = 0 # LINEAR_VOX_TO_VOX
+nxforms   = 1
+mean      = 0.0000 0.0000 0.0000
+sigma     = 10000.0000
+1 4 4
+3.124095916748047e+00 -2.993918396532536e-02 -8.824434876441956e-02 3.380017089843750e+01
+-7.292380183935165e-02 -1.901555061340332e+00 -3.172848463058472e+00 2.405808868408203e+02
+-1.820227503776550e-02 2.479679346084595e+00 -2.434180974960327e+00 7.082101440429688e+01
+0.000000000000000e+00 0.000000000000000e+00 0.000000000000000e+00 1.000000000000000e+00
+src volume info
+valid = 1  # volume info valid
+filename = /home/oesteban/tmp/fmriprep-ds005/fprep-work/fmriprep_wf/single_subject_01_wf/func_preproc_task_mixedgamblestask_run_01_wf/bold_reg_wf/bbreg_wf/bbregister/uni_xform_masked.nii.gz
+volume = 64 64 34
+voxelsize = 3.125000000000000e+00 3.125000000000000e+00 4.000000000000000e+00
+xras   = -1.000000000000000e+00 0.000000000000000e+00 0.000000000000000e+00
+yras   = 0.000000000000000e+00 1.000000000000000e+00 0.000000000000000e+00
+zras   = 0.000000000000000e+00 0.000000000000000e+00 1.000000000000000e+00
+cras   = 1.000000000000000e+00 2.800000000000000e+01 -3.100000000000000e+01
+dst volume info
+valid = 1  # volume info valid
+filename = /oak/stanford/groups/russpold/data/openfmri/derivatives/ds000005/freesurfer-6.0.1/sub-01/mri/orig.mgz
+volume = 256 256 256
+voxelsize = 1.000000000000000e+00 1.000000000000000e+00 1.000000000000000e+00
+xras   = -9.999999403953552e-01 0.000000000000000e+00 0.000000000000000e+00
+yras   = 0.000000000000000e+00 0.000000000000000e+00 -9.999999403953552e-01
+zras   = 0.000000000000000e+00 9.999999403953552e-01 0.000000000000000e+00
+cras   = -9.999847412109375e-01 -5.000015258789062e+00 -1.000038146972656e+00
+subject sub-01
+fscale 0.100000

nitransforms/tests/data/regressions/T1w_scanner.nii.gz

@@ -0,0 +1,5 @@
+#Insight Transform File V1.0
+#Transform 0
+Transform: AffineTransform_double_3_3
+Parameters: 0.99971085786819458 0.0058247237466275692 0.023335624486207962 0.0095805395394563675 0.79349809885025024 -0.608498215675354 -0.022061100229620934 0.60854566097259521 0.79321271181106567 -5.5388064384460449 -45.559787750244141 -48.801029205322266
+FixedParameters: 0 0 0

nitransforms/tests/data/regressions/bbregister.tfm

@@ -1,12 +1,14 @@
+# This file was generated with bbregister, with fMRIPrep-20.0.5's settings
+# mri_concatenate_lta from-fsnative_to-bold_mode-image.lta from-scanner_to-fsnative_mode-image.lta from-scanner_to-bold_mode-image.lta
 type      = 0 # LINEAR_VOX_TO_VOX
 nxforms   = 1
 mean      = 0.0000 0.0000 0.0000
 sigma     = 1.0000
 1 4 4
--3.124080896377563e+00 2.981145866215229e-02 8.914728462696075e-02 1.741926879882812e+02 
--1.405486371368170e-02 1.859627604484558e+00 -1.825850725173950e+00 5.312585067749023e+01 
-5.505303665995598e-02 1.426339745521545e+00 2.379452466964722e+00 1.154438781738281e+01 
-0.000000000000000e+00 0.000000000000000e+00 0.000000000000000e+00 9.999998807907104e-01 
+-3.124080896377563e+00 2.981145866215229e-02 8.914728462696075e-02 1.741926879882812e+02
+-1.405486371368170e-02 1.859627604484558e+00 -1.825850725173950e+00 5.312585067749023e+01
+5.505303665995598e-02 1.426339745521545e+00 2.379452466964722e+00 1.154438781738281e+01
+0.000000000000000e+00 0.000000000000000e+00 0.000000000000000e+00 9.999998807907104e-01
 src volume info
 valid = 1  # volume info valid
 filename = /home/oesteban/tmp/fmriprep-ds005/fprep-work/fmriprep_wf/single_subject_01_wf/func_preproc_task_mixedgamblestask_run_01_wf/bold_reg_wf/bbreg_wf/bbregister/uni_xform_masked.nii.gz