Example 6.  Reading a Multi-field and Mixed-type Vdata with Packing

This example illustrates the use of VSread/vsfread to read part of a mixed data
vdata and VSfpack/vsfnpak/vsfcpak to unpack the data read.

The program reads the vdata "Mixed Data Vdata" that was written to the
file "Packed_Vdata.hdf" by the program in Example 4.  In Example 6, all
values of the fields "Temp" and "Ident" are read.  The program unpacks
and displays all the values after reading is complete.  Again, note
that in C only one call to VSread and one call to VSfpack are made to read
and unpack all N_RECORDS records. In Fortran, data is read with one call to
vsfread, but each field is unpacked using separate calls to vsfnpak and vsfcpak.