The 2304 unique Euler angle values for a rank-2 tensor with no skew (12 axis orders, 2 frames of
ref., 2 directions (forwards + reverse), 4 rotational symmetries (pi rotations about each
eigenvector), 2 handednesses (left + right), and 6 eigenvalue orders) are now all properly handled.
The resultant Euler angle values are a single set of the 2304, matching that already used in relax
(zyz, rotated axis system, reverse direction, rotational symmetry collapse to 0 <= alpha, beta,
gamma <= pi, right handedness, and Dx <= Dy <= Dz).
