BUG: Read vectors as scalars

3-vectors were read as Vectors and placed on PointData.
All other vector lengths are read as multi-component Scalars
on PointData.

This patch treats all vectors as scalars to be consistent.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22607 3bd1e089-480b-0410-8dfb-8563597acbee