netcdf-c

1. corrected the nc_get_varm/put_varm documentation
   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