relax SVN archive

Fixes for the alignment tensor unit tests (due to object renaming).

N-state model fix for the alignment tensor object renaming.

Cut and paste bug fix for the alignment tensor diagonalisation function calc_A_diag().

Alphabetical reordering of the functions.

Expanded the alignment tensor object.

The 'tensor' and 'tensor_diag' objects are no more. New structures include:
A
A_5D
A_diag
eigvals
S
S_5D
S_diag
P
P_5D
P_diag

'Aii_unit', where i is one of x, y, or z has been renamed to 'unit_i'. 'rotation' has been renamed
to 'R'.

Additional modifications to the alignment tensor print out to show more information.

Modified the alignment tensor print out to be more compact.

Fixed the Euler angle conversion unit tests for the beta = 0 degeneracy.

Expanded the maths_fns.rotation_matrix.R_to_euler_zyz() docstring to document the beta = 0 case.

Bug fix for maths_fns.rotation_matrix.R_to_euler_zyz() for the case where beta = 0.

This uses the sub-matrix components of the z rotation to put the full rotation into alpha (gamma
is zero).