Fix for bug #21187 - the corrupted PDB issue with protons atom numbers of zero.

The bug at https://gna.org/bugs/?21187 was reported by Martin Ballaschk (https://gna.org/users/mab).

The fix was to allow for spin containers in the relax data store to have the same atom number, as
long as the atom names are different.  Note - this may cause problems in the future so a better
solution might have to be found.
Fix for the unit tests for the bug fix of r21051.