relax SVN archive

Implemented the models argument for the structure.web_of_motion user function.

This was previously not being used and was caught by the Structure.test_web_of_motion_12 system
test.

Created the Structure.test_web_of_motion_12 system test to show how model sets are currently ignored.

Small fixes for the Structure.test_web_of_motion_all system test.

The structure.web_of_motion user function can now handle file objects as well as file names as input.

Created the Structure.test_web_of_motion_all system test.

This is to check the new structure.web_of_motion user function.

A new PDB file with 3 models and a few atoms for testing of the structure.web_of_motion user function.

Created the structure.web_of_motion user function.

This is used to create a special PDB file which represents the atomic motions between different
structural models. Identical atoms of the selected models are concatenated into one model, within
a temporary internal structural object, and linked together using PDB CONECT records.

Fix for the assembly of atomic positions for the frame order analysis.

This is for the _minimise_setup_atomic_pos() method. Previously the warning "RelaxWarning:
Averaging the 1 atomic positions for the PCS for the spin 'x'" was being given if a single atomic
position was found.

Bug fix for the frame order analysis when multiple models are present.

The averaging of the atomic positions was not working and instead a sum was being performed.

Fix for the frame order grid search for when the pivot point is to be optimised.

The construction of the custom grid point array was failing when the pivot point is to be optimised.