* Added support for `maxOccurs=unbounded` directly in `array_fields` (aa1c6b4890e9124cd789469d4e03834ce3d29023).
* Added support for `'abstract': True` model option overriding `xs:complexType[abstract]` attribute (32b45da593ab8f27094bda338bc1fb7631a80aa3).
* Added support for `xs:all` (6f539d54bd32a4b0d7c626a199e8362c7ca76c4c).
* Added support for `xs:attributeGroup` (bd49b5517605602aef0dc7d95c4191c82225efcc).
* Added support for `xs:group` (0982d0da5924795fed64e76f4daeab5140aecdd1).
* Never generate `OneToOneField`, it's a wrong thing to do most of the time (1c3da09b52073be9d50f0150de3363520a20bf72).
* Fixed array_fields with a single-attribute `xs:complexType` (6083c834a08f250850ca4b589d19dc9b0f1c820c).
* Fixed primitive type introspection for deep `xs:simpleContent/xs:restriction[base]` inheritance (183de02bb06d5065efcc9c2ac98cd80d9a5416d3).
* Don't output `default=` model field option when `null=True` (e060cfb2dd734556be1d3b3a9d71af2e34cdadb5).
* Fixed flattening deep `xs:complexType/xs:complexContent/xs:extension[base]` inheritance (bac0f5f3e49d2f174cdcdbae8cb44afdc941f83a).
* Fixed an assertion when there are only attributes in `xs:complexType/xs:complexContent/xs:extension` (ce5943baffea1cee9b74b8df4d0396dd558ce2cf).