Refs #2443 -- fixed format_dtdelta on SQLite

A test failed on Python 2 32-bit.
Fixed #17946 -- Fixed deserialization of self-referencing M2M fields

Thanks Philip Mountifield for the report and excellent analysis, and
Simon Charette for the review.
Added RasterSource/GDALBand GDAL objects

Based on Daniel Wiesmann's raster branch. Thanks Daniel Wiesmann
and Tim Graham for the reviews. Refs #23804.
Fixed #21414 -- Removed RelatedObject and deprecated Field.related.
Removed model_package test dependency on contrib.sites
Removed admin_util test dependency on contrib.sites
Removed unneeded null param to ManyToManyField
Added migration for site test app depending on contrib.sites
Replaced DatabaseCreation sql methods by schema editor equivalents

Also used schema editor in migrate to sync unmigrated apps (sync_apps).
Refs #22340. Thanks Tim Graham for the review.
Removed models.Field.bind() -- unused/undocumented since at least 1.0.
Fixed #24037 -- Prevented data loss possibility when changing Meta.managed.

The migrations autodetector now issues AlterModelOptions operations for
Meta.managed changes instead of DeleteModel + CreateModel.

Thanks iambibhas for the report and Simon and Markus for review.
Fixed #24035 -- Clarified docs on CACHE_MIDDLEWARE_KEY_PREFIX vs KEY_PREFIX
Fixed some docs spelling mistakes.
Moved test correction from 5b1fb0a75
Ignored deprecation warnings for CreationIndexesTests
Fixed typo in test_utils comment.
Fixed #20349 -- Moved setting_changed signal to django.core.signals.

This removes the need to load django.test when not testing.
Added a test to ensure bad assignation to M2M doesn't clear data

Refs #14394.
Complemented pickle test for ValuesQuerySet with related field

Refs #14515.
Fixed #22461 -- Added if-unmodified-since support to the condition decorator.