The fix includes the following changes.
1. Checking and using the default file format at file create time is now
done only when the create mode (argument cmode) does not include any
format related flags, i.e. NC_64BIT_OFFSET, NC_64BIT_DATA,
NC_CLASSIC_MODEL, and NC_NETCDF4.
2. Adjustment of cmode based on the default format is now done in
NC_create() only. The idea is to adjust cmode before entering the
dispatcher's file create subroutine.
3. Any adjustment of cmode is removed from all I/O dispatchers, i.e.
NC4_create(), NC3_create(), and NCP_create().
4. Checking for illegal cmode has been done in check_create_mode() called
in NC_create(). This commit removes the redundant checking from
NCP_create().
5. Remove PnetCDF tests in nc_test/tst_names.c, so it can focus on testing
all classic formats and netCDF4 formats.
Two new test programs are added. They can be used to test netCDF with and
without this commit.
1. nc_test/tst_default_format.c
2. nc_test/tst_default_format_pnetcdf.c (use when PnetCDF is enabled).
