OPT: Correct header after padding using qform instead of sform. (fix #518)
OPT: Correct header after padding using qform instead of sform. (fix #518)

Former-commit-id: d75201da036f6001399d3e11dd829b2e020d633d
Former-commit-id: e3ada7b31e0905a8c077fcc4822f030feecd604e
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox