relax SVN archive

Created maths_fns.order_parameters.iso_cone_theta_to_S() function for angle to order param conversion.

The isotropic cone parameter cone_theta is now being unpacked and stored after optimisation.

Bug fix for the frame order _update_model() method for the isotropic cone.

The cone angle parameter cone_theta was incorrectly referenced.

The isotropic cone frame order model now uses the full eigenframe.

This is necessary to define the torsion angle restriction.

The frame order specific module now uses spherical_to_cartesian().

Shifted frame_order_matrix_ops.generate_vector() to coord_transform.spherical_to_cartesian().

The function input has been modified to accept a spherical coordinate vector.

Switched the theta and phi angles in cartesian_to_spherical() to match the rest of relax.

Created a new module for performing coordinate transformations.

The new function cartesian_to_spherical() has been added as the first conversion.

Fixed another typo in populate_2nd_eigenframe_iso_cone().

Fixed a typo in populate_2nd_eigenframe_iso_cone().