Do we need tenmat and sptenmat?

[tgkolda]

I'm not sure that tenmat and sptenmat are needed. These were originally created in order to move back and forth from a tensor to different unfoldings of a tensor. This is almost never needed in practice. I would recommend getting rid of this functionality and replacing it with "unfold" functions that produce a matrix. I haven't eliminated these classes in MATLAB, but I don't know anywhere that they are actually used.