`mean_aligned_angular_distance` w/ symmetry

[j-c-c]

Feature request from user @itamero:

Due to symmetry ambiguity, when interested in comparing estimated rotations to ground truth rotations we actually want the minimal difference up to multiplication by some rotation group element. Would be nice if some of the Image methods, like mean_angular_distance or mse could have an option to compare the metric across the symmetry group.

We handle symmetry in testing for commonlines methods for symmetric molecules. For example here. This code could be adapted to handle arbitrary symmetry and added to the diagnostic tools mean_aligned_angular_distance and mse.