Ihm

=================
- Improve reading of mmCIF files with incomplete data (86, 87) or with
categories in an unexpected order (85).
- Bugfix: fix sanity check for multiple atoms with the same atom_id and
seq_id to handle bulk water (where such duplicates are OK) (88).

=================
- :class:`ihm.protocol.Step` now takes an ``ensemble`` flag, to indicate
whether the modeling involved an ensemble, and which defaults to True if
the system contains at least one :class:`ihm.model.Ensemble` (83).
- When reading an incomplete mmCIF file, such as that generated by some
versions of PyMOL, python-ihm will now fill in missing entity-related
information by guessing the sequence from the atom_site table (67).
- Bugfix: :class:`ihm.flr.RefMeasurementGroup` objects are now read
from mmCIF files correctly.

=================
- The :class:`ihm.dumper.IgnoreVariant` class can now be used to exclude
selected categories from the mmCIF/BinaryCIF output.
- The _pdbx_nonpoly_scheme CIF table should now fully comply with the
PDBx dictionary.
- Atoms are now checked at file-output time to ensure that a given model
chain does not contain multiple atoms with the same atom_id and
seq_id (81).

=================
- Add support for a long description of the system (like an abstract)
using struct.pdbx_model_details (80).
- Bugfix: correctly read mmCIF files with missing entity.type.

=================
- Output mmCIF files containing non-polymers should now validate against
the PDBx dictionary (76).
- Bugfix: non-polymers that are erroneously marked as polymers in
the input mmCIF can now be read in without causing a Python
exception (78).
- Bugfix: strings starting with an underscore (e.g. chain names) are now
quoted in mmCIF output to conform to the CIF syntax (75).

=================
- :class:`ihm.Citation` now takes a ``is_primary`` argument, which can
be used to denote the most pertinent publication for the modeling.
- Improved support for non-standard residues, and for standard amino acids
used as nonpolymers.