Proposal: Multidimensional opSlice solution

[Norbert Nemec]

Don wrote:
> Multidimensional slices normally result in appallingly inefficient use 
> of caches.

Indeed, cache usage is a challenge. My general approach would be fairly 
conservative: give the user full control over memory layout, but do this 
as comfortably as possible. Provide good performance for straightforward 
code but allow the user to tweak the details to improve performance

A library function that takes several arrays as input and output should 
allow arbitrary memory layouts, but it should also specify which memory 
layout is most efficient.

In any case, I think that the expressiveness of multidimensional slices 
is worth having them even if the performance is not optimal in every 
case with the first generation of libraries.