ENH: Support different index space orderings

This commit adds to the ExtentUtilities support for
differnt index space orderings for mapping structured
coordinates, an IJK-tuple, to a linear index. Currently,
ExtentUtilities supports indexing first in the
i-, then j-, then k-directions, as well as,
first in the k-, then j-, and then i-directions
(used in HACC). The calling application can specity
the desired ordering via an optional parameter in GetLinearIndex()
or GetStructuredCoordinates(). Different orderings can be added in
the future as needed.
ENH: Add test for ExtentUtilities
ENH: Implement ExtentUtilities::WithiExtent
ENH: Delete dax results from repo
ENH: Move older implementation to reference folder
WIP: Refactoring...
WIP: Adding stream-count utility
WIP: Virtual Grid
WIP: stream-count