relax SVN archive

Fixes for the rotor frame order system test data.

The first structure of the distribution was missing!

The frame order torsion angle cone_sigma_max is now forced to be positive.

Optimisation sometimes comes up with the negative of the angle, as both the negative and positive
angles give the same result, so now the angle is always unpacked after optimisation as the absolute
value.

Fixes for the test data committed previously (r14954).

Created a frame order test model for the rotor model when there are only two states.

Created the Frame_order.test_cam_rotor system test.

This is the rotor model with the rotation axis being the pivot-CoM vector.

Created a frame order rotor test model whereby the rotation axis is the pivot-CoM vector.

The rotation is a total of 60 degrees about the pivot-CoM vector.

Added a check to prevent the frame order grid search from being too big causing out of memory errors.

Created the Frame_order.test_cam_rotor2 system test.

This checks the frame order rotor model whereby the rotation axis is perpendicular to the pivot-CoM
vector.

Created a frame order rotor test model whereby the rotation axis is perpendicular to the domain.

The rotation is a total of 60 degrees about an axis perpendicular to the pivot-CoM vector. The
'rotor' test model directory is reserved for a model whereby the rotation axis is the pivot-CoM
vector.

Properly added the add_atom() and connect_atom() methods to the structural API.