Each of the file hdf_mag_vec_*.c allows read and write access to a single
HDF file.  Therefore to copy data from one file to another 2 sets of these 
routines are needed.  

To make the file hdf_mag_vec_in.c take the file ../hdfsubs/hdf_mag_vec.c 
and replace "_mag_vec" with "_mag_vec_in" and similarly for
hdf_mag_vec_out.c.