* Converted the ``libraries`` and ``builtins`` globals of
  ``django.template.base`` into properties of the Engine class.
* Added a public API for explicit registration of libraries and builtins.

This is a security fix; disclosure to follow shortly.

Thanks Sam Cooke for the report and draft patch.

Thanks to Tim and Anssi for the review.

Avoided split_exclude() for Q when used as an expression.

Refs #24503.

This was broken in c2bc1cef (refs #23763).

Thanks Wim Feijen for the report.

Thanks Markus Holtermann for review.

It has been superseded by the converter infrastructure.

Took advantage of the new database adapters and converters.

The primary use case is to interact with a third-party database (not
primarily managed by Django) that doesn't support time zones and where
datetimes are stored in local time when USE_TZ is True.

Configuring a PostgreSQL database with the TIME_ZONE option while USE_TZ
is False used to result in silent data corruption. Now this is an error.

This mirrors convert_xxxfield_value nicely, taking advantage of the
adapter/converter terminology which is commonly used by DB-API modules.

Refs #23820.

Fixed #19738.

Refs #17755. In order not to introduce a regression for raw queries,
parameters are passed through the connection.ops.value_to_db_* methods,
depending on their type.

Put the types in the same order and checked for None consistently.

Refs #23820.