Add a NetCDF header file containing C macros.

	modified:   CMakeLists.txt
	new file:   include/netcdf4_macros.h
	modified:   src/netcdf4/netcdf4_example_01.c
Init a second example od a NetCDF file writting.

	new file:   src/netcdf4/netcdf4_example_02.c