symmetries (sysems) we want to be able to handle

[js850]

non periodic systems

best alignment, exact match, point group order, list of symmetry operations (rotations and presence of inversion symmetry)

1. translations
2. rotations
3. permutations
4. inversions
5. all combinations of 1-4

periodic systems (fixed box)

1. exact match (should be easy. in N^3?)
2. best alignment. This is very hard. By default maybe you should only optimize permutations?

crystals

1. space group / point group order
2. exact match
3. best aligment. Very very hard.