dat1New: Use H5LT API to simplify attribute writing

Saves many lines.
Protect printf when status bad
Configure new primitive arrays with unlimited max size

Not sure how well this will work. Seems that unlimited max size
is required to allow the primitive to be resized but that requires
that the chunking size is specified. HDS has no way of getting
a hint from the user regarding chunk sizes.
Now create arrays of structures

Support routines do not yet support this so you can not
correctly use datName or hdsTrace, and datCell is not
yet implemented.
Comment about use of H5S_UNLIMITED
Factor out hdsTracing test code