Merge branch 'master' into develop

CHANGELOG.txt

CMakeLists.txt

actions/ost-compare-ligand-structures

docker/Dockerfile

modules/doc/actions.rst

modules/io/doc/io.rst

modules/io/doc/mmcif.rst

modules/io/doc/structure_formats.rst

modules/io/pymod/CMakeLists.txt

modules/io/pymod/__init__.py

modules/io/pymod/export_sdf_io.cc

modules/io/pymod/wrap_io.cc

modules/io/src/mol/entity_io_sdf_handler.cc

modules/io/src/mol/mmcif_reader.cc

modules/io/src/mol/sdf_reader.cc

modules/io/src/mol/sdf_reader.hh

modules/io/src/mol/sdf_str.cc

modules/io/src/mol/sdf_str.hh

modules/io/tests/test_io_sdf.py

modules/io/tests/testfiles/sdf/dative_bond.sdf