Expands the ND matrix A by cell replication, and returns the result.
If the vertical scale factor is omitted, it is assumed to be
the same as the horizontal. Note that the horizontal-before-vertical
ordering of arguments is consistent with image processing, but contrary
to Matlab's rows-before-columns convention.
We use "Tony's Trick" to replicate a vector, as explained
Matlab Technote 1109, section 4.
Also see ScaleRect