relax SVN archive

These are now provided by the spin.isotope user function and the dipole_pair user functions. The
eliminated parameters are:
'r' - replaced by dipole_pair.set_dist or dipole_pair.read_dist,
'xh_vect' - replaced by dipole_pair.unit_vectors,
'heteronuc_type' - replaced by spin.isotope,
'proton_type' - replaced by spin.isotope,
'attached_proton' - replaced by dipole_pair.define.