JPSSnagg

Fill Values do not need to be written if all the data in a dataset consists solely of fill values.
 Added code to check for datasets with storage size 0 and skip copying the granule hyperslabs for that dataset.  Also removed writing of fill values in datasets for missing granules.  It may be possible to check each hyperslab to see if the data is entirely fill values before writing it, even if other hyperslabs have real data, but that has not been done in this checkin.

Tested on jam & koala, icc and gcc.