Peewee

* More efficient implementation of model dependency-graph generation. Improves
performance of recursively deleting related objects by omitting unnecessary
subqueries.
* Added `union()`, `union_all()`, `intersect()` and `except_()` to the
`Model`-specific query implementations. This was an oversight that should
have been patched in 3.3.2, but is fixed in 3.3.3.
* Major cleanup to test runner and standardized test skipping logic to
integrate with standard-library `unittest` conventions.

[View commits](https://github.com/coleifer/peewee/compare/3.3.2...3.3.3)

* Add methods for `union()`, `union_all`, `intersect()` and `except_()`.
Previously, these methods were only available as operator overloads.
* Removed some Python 2.6-specific support code, as 2.6 is no longer officially
supported.
* Fixed model-graph resolution logic for deferred foreign-keys.
* Better support for UPDATE...FROM queries (Postgresql).

[View commits](https://github.com/coleifer/peewee/compare/3.3.1...3.3.2)

* Fixed long-standing bug in 3.x regarding using column aliases with queries
that utilize the ModelCursorWrapper (typically queries with one or more
joins).
* Fix typo in model metadata code, thanks klen.
* Add examples of using recursive CTEs to docs.

[View commits](https://github.com/coleifer/peewee/compare/3.3.0...3.3.1)

* Added support for SQLite's new `ON CONFLICT` clause, which is modelled on the
syntax used by Postgresql and will be available in SQLite 3.24.0 and onward.
* Added better support for using common table expressions and a cleaner way of
implementing recursive CTEs, both of which are also tested with integration
tests (as opposed to just checking the generated SQL).
* Modernized the CI environment to utilize the latest MariaDB features, so we
can test window functions and CTEs with MySQL (when available).
* Reorganized and unified the feature-flags in the test suite.

[View commits](https://github.com/coleifer/peewee/compare/3.2.5...3.3.0)

* Added `ValuesList` for representing values lists. [Docs](http://docs.peewee-orm.com/en/latest/peewee/api.html#ValuesList).
* `DateTimeField`, `DateField` and `TimeField` will parse formatted-strings
before sending to the database. Previously this only occurred when reading
values from the database.

[View commits](https://github.com/coleifer/peewee/compare/3.2.4...3.2.5)

* Smarter handling of model-graph when dealing with compound queries (union,
intersect, etc). 1579.
* If the same column-name is selected multiple times, first value wins. 1579.
* If `ModelSelect.switch()` is called without any arguments, default to the
query's model. Refs 1573.
* Fix issue where cloning a ModelSelect query did not result in the joins being
cloned. 1576.

[View commits](https://github.com/coleifer/peewee/compare/3.2.3...3.2.4)