Moved up T1w processing bloc and rely on T1w segmentation and labeling

[jcohenadad]

• Fixes Consider doing the segmentation and vertebral labeling only on the MPRAGE #49

[jcohenadad]

2dba774 implements a registration methods based on slicereg. The only scans for which it does not work are sub-04 CP, patient and volume.

Indeed, they are pretty far apart:

The registration, even when done on the cropped image, is slightly failing:

I'll try with a tight mask.

[jcohenadad]

With mask: