ENH: Use SpaceDimension - 1 instead of 2

git-svn-id: https://svn.bigr.nl/elastix/trunkpublic@4292 4d348492-3962-11de-aa85-65a2020054a3
ENH: Crop B-spline domain to fMask

git-svn-id: https://svn.bigr.nl/elastix/trunkpublic@4293 4d348492-3962-11de-aa85-65a2020054a3