NEW: script to concatenate bvals
NEW: script to concatenate bvals

Former-commit-id: 522ae719411218d501b3f098271c518b75ae3e46
Former-commit-id: aabd50732c486d57213d6562a55704e8de417c02
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox