[1.6.x] Made an aggregate test pass with spatialite backend

backends.tests.SqliteAggregationTests was failing with spatialite.

Backport of 550b6195ed from master
[1.6.x] Fixed #22753 -- Documented ability to use a note with the {% comment %} tag.

Backport of e020894470 from master
[1.6.x] Removed erroneous trailing comma in OLMapWidget.js.

Backport of c5226eb72a from master
[1.6.x] Fixed #22710 -- Amended aggregation note for empty QuerySets

Thanks smeaton for report and Joël Rochat for spell check

Backport of 7f27cca5c5 from master
[1.6.x] Fix missing highlighting in some code examples

Backport of 84cafc2b35 from master
[1.6.x] Removed duplicate "Deprecated in Django A.B" text in docs.

sphinx 1.2+ adds this text itself.

Backport of 7f4347b176 from master
[1.6.x] Fixed #22801 -- Added 'www.' to diveintopython.net links

Backport of f97c53c098 from master
[1.6.x] Fixed #22813 -- Updated Pillow URL in documentation

Backport of dfa3505ff1 from master.
[1.6.x] Fixed #22818 -- Clarified you need to cd into the Django clone.

Thanks Josh Parris.

Backport of bcc3d2b978 from master
[1.6.x] Fixed #22349 -- Added a note clarifying `RawQuerySet` has no `__len__`.

Thanks cdestigter for the report.

Backport of 2d425116e2 from master
[1.6.x] Fixed #22842

Backport of 7a1f8414c3b71b6af03e5be9f5f8db115551c410 from master.
[1.6.x] Fixed #14481 -- Documented implicit "through" class created by ManyToManyField.

Thanks to jonathanmorgan for the report and initial patch.

Backport of de90129070 from master
[1.6.x] Fixed #22859 -- Improved crossDomain technique in CSRF example.

Thanks flisky for the report.

Backport of 0be4d64487 from master
[1.6.x] Fixed #22514 -- Prevented indexes on virtual fields [postgres].

Backport of 78c32f1caa from master
[1.6.x] Created import-time test temp dirs in known location

Refs #17215. In the same spirit as 5de31cb8cb.
Backport of 809362518d from master.
[1.6.x] Fixed typo in middleware docs.

Function definition should have an ending colon.

Backport of 48241ec from master
[1.6.x] Improved documentation for QueryDict.

Backport of 7f4e2ef1e9 from master
[1.6.x] Fixed copy/paste typos in StreamingHttpResponse doc.

Backport of e9c730f6be from master
[1.6.x] Fixed #22912 -- Warned about a common mistake in tutorial 5.

Backport of 1e8411259f from master
[1.6.x] Fixed a French translation in contrib.auth

Refs #22929.