to indicate that they only work for atomic types,
not user defined types.
2. modified NCDEFAULT_{get/put}_vars to no longer use
nc_get/put_varm. They now directly use nc_get/put_vara
directly. This means that nc_get/put_vars now work
properly for user defined types as well as atomic types.
3. Added test cases for get_vars/put_vars with a
user defined type. Tests placed into
nc_test/tst_compounds.c
