Yolo, this code is totally untested. Xavier, please give it a try ;)

Following fixes in cd701347, setting seqres=True is no longer required
for these things to work.

A null character is added by OST in case of empty insertion code. This is not part of the actual insertion code, and could make it harder for third party software to handle our output.

CAD score computation requires residue numbers in model and reference
to match. This raises an error in the Scorer object otherwise.
Catch this early on and raise an error specific to compare-structures
action with instructions on how to get rid of it.

Mainly for reporting in the compare-structures action
residues are reported as strings in format:
<cname>.<rnum>.<ins_code>, atoms are reported as
<cname>.<rnum>.<ins_code>.<aname>. This changes behaviour of
compare-structures and ost.mol.alg.stereochemistry
(ToJSON functions of violation info objects for the latter).

A global chain mapping can now be enabled with --global-chain-mapping as
a complement to the existing local chain mapping. This can be evaluated
for the scoring paper.

This makes the ligand scoring script more independent of an up-to-date
compound library, which is a strong requirement of Molck.
This was a problem for the April 2023 Modeling Championship where the
script was run with an out of date library and the element of an atom of
the ligand was silently changed, preventing the symmetry correction to
find isomorphisms and resulting in the absence of scores.

This may be necessary in case SDF ligands have the same chain/residue
number, which can happen with some input.

This should clarify what the binding site.

- Tell the user that biounit indices are 0-based
- More info in output on what chains are actually processed