Added a Trac-related item to the release checklist.
1.5 is no longer "UNDER DEVELOPMENT".

Thanks to Bruno Renie for reporting.
Fixed #12823 -- Was already fixed in master, tests added

Also added a little improvement to sql/query.py to get rid of
non-necessary IS NOT NULL check.
Fixed #5241 -- Kept active transalation in LocaleMiddleware.process_response.
Fixed #19937 - Typo in class-based views intro.
Implemented persistent database connections.

Thanks Anssi Kääriäinen and Karen Tracey for their inputs.
Fixed tests broken in 2ee21d9.
Fixed #19929 -- Improved error when MySQL doesn't have TZ definitions.

Thanks tomas_00 for the report.
Fixed #16612 -- Improved has_changed detection for localized field values

Thanks Simon Charette for the review.
Fixed #18898 -- Added tests with a fix for ModelMultipleChoiceField
Fixed #19960 -- Fixed sentence in contrib.auth signals docs

Thanks edd at slipszenko.net for the report.
Removed unused options copy in flush

This was used at the time the 'database' option did not default to
DEFAULT_DB_ALIAS in make_option.
Added import forgotten in 2ee21d9.

Thanks ratsonale for spotting this mistake.
Added a context manager to capture queries while testing.

Also made some import cleanups while I was there.

Refs #10399.
Fixed #10399 -- Tested that o2o field updates are not constrained by an inner query.
Import `CaptureQueriesContext` from its original module.
Add a BinaryField model field

Thanks Michael Jung, Charl Botha and Florian Apolloner for review
and help on the patch.
Added support for serializing BinaryField
Add introspection support for BinaryField
Reordered methods in database wrappers.

* Grouped related methods together -- with banner comments :/
* Described which methods are intended to be implemented in backends.
* Added docstrings.
* Used the same order in all wrappers.