Fix for a bug introduced at r16453.
The structure.vectors user function will now store single vectors as a 3D, rank-1 array. In some cases this was being stored as a list of 3D, rank-1 arrays which was then failing in with the RelaxMultipleVectorError in the model-free code.
Authored by: bugman 2012-05-25
Parent: [r16453]
Child: [r16455]
