The new function 'self.write_pdb_file()' has been added which creates a properly formatted PDB file.
It creates HET, HETNAM, and FORMUL records for the pseudo-residue 'TNS'. It also adds HETATM
records for each atom, adds the TER record, and then connects the appropriate atoms using CONECT
records. The file is terminated with the MASTER and END records. For a description of this, see
the post at https://mail.gna.org/public/relax-devel/2006-10/msg00136.html (Message-id:
<7f080ed10610252045r3dcbba38q58aa53142af96e5a@...>).
The function 'self.create_tensor_pdb()' has been modified to create the data for the new
'self.write_pdb_file()' function.
