The multidimensional array support is temporarily housed here until it
is moved into either Teuchos or its own package.  This should happen
before Trilinos release 10.0

- version_1 is the original MDArray where the Array was templated on a
DimNatural/DimFortran object that had all dimensioning.

- version_2 is the current incarnation in phdmesh.  It removed the
nested template by merging the DimNatural and DimFortran objects into
the Array itself.

- version_3 refactor still in phdmesh.  Change to single array and now
templated on an enumerated type for the Natrual/Reverse ordering.
Also seems to have changed the dimension tags.  Will have to update
all tests.  Need to add new template argument to both MDALayout and
MDField that is the ordering argument.
