Add placeholder datVec

datVec does not vectorise yet. It just clones the locator.
Actually call datVec

Remove all the commenting out of datVec in the Get and
Put routines now that a datVec placeholder exists.
Forgot to commit the prologue for datChscn
Cell name must match HDS ordering

So we must use the HDS dims and not dimensions that have
been imported to HDF5 (which may or may not include
transposition).