Fix for bug #21561, the structure.create_diff_tensor_pdb user function failure with no simulations.
Bug #21561 (https://gna.org/bugs/?21561) was reported by Martin Ballaschk (https://gna.org/users/mab).
The problem was that the simulation axes of the tensor PDB file were not being initialised correctly when no Monte Carlo simulations had been run.
Authored by: bugman 2014-01-30
Parent: [r22077]
Child: [r22079]