Convert an array of cell indices in an (ni-1)-by-(NJ-1)-by-(NK-1) logically rectangular grid
of cells into the array of len(LIST)-by-2-by-2-by-2 cell corner indices in the corresponding ni-by-NJ-by-NK
array of vertices. The algorithm used is described in section ``More slice3 details''. Note
that this computation in Yorick gives an absolute offset for each cell quantity in the grid. In Yorick it
is legal to index a multidimensional array with an absolute offset. In Python it is not. However, an array
can be flattened if necessary.
Other changes from Yorick were necessitated by row-major order and 0-origin indices, and of
course the lack of Yorick array facilities.
