[1.5.x] Fix grammatical errors in email documentation

Backport of 43f213e475 from master
[1.5.x] Fixed #16436 -- defer + annotate + select_related crash

Correctly calculate the ``aggregate_start`` offset from loaded fields,
if any are deferred, instead of ``self.query.select`` which includes all
fields on the model.

Backpatch of 69f7db153d8108dcef033207d49f4c80febf3d70 from master.
[1.5.x] Fixed #21248 -- Skipped test_bcrypt if no py-bcrypt found

Pre 1.6 Django worked only with py-bcrypt, not with bcrypt. Skipped
test_bcrypt when using bcrypt to avoid false positives.
[1.5.x] Small improvements to docs/topics/db/models.txt

Backport of 695bc0d191 from master
[1.5.x] Minor edits to docs/topics/db/queries.txt.

Backport of 8bfc7cc64c from master
[1.5.x] Fixed #15582 -- Documented how TransactionTestCase.multi_db affects fixtures.

Thanks slinkp for the suggestion.

Backport of dd839a2dfd from master
Fixed #21261 -- Added missing import in RedirectView docs

Thanks yokomizor.
[1.5.x] Fixed #21256 -- Error in datetime_safe.datetime.combine.

Backport of d9b6fb8 from master
[1.5.x] Fixed #21027 -- Updated tutorial 5 docs to link to management shell command page.

Backport of 13ddf0e002 from master
[1.5.x] Fixed #21264 -- Incorrect RST usage in docs

Backport of 8fc63087f6 from master
[1.5.x] Fixed #21210 -- Documented when runserver doesn't auto-restart.

Thanks gergely at polonkai.eu for the suggestion.

Backport of 9b7d38ed5a from master
[1.5.x] Fixed #20962 -- Documented that template tag render() may raise exceptions.

Thanks Keryn Knight for the report.

Backport of e077224f4a from master
[1.5.x] Fixed #21223 -- Added form.id_for_label to topic guide.

Thanks ebertti at yahoo.com.br for the suggestion.

Backport of 018e2c055a from master
[1.5.x] Fixed #21006 -- Added example code for overriding methods on an InlineFormSet.

Thanks treysta at gmail.com for the suggestion.

Backport of 9bfe66164e from master
[1.5.x] Improvement on InlineFormSet doc, refs #21006

Backport of 944a2bb7c1 from master
[1.5.x] Fixed bug causing CSRF token not to rotate on login.

Thanks Gavin McQuillan for the report.

Backport of ac4fec5ca2 from master
[1.5.x] Added a warning regarding session security and subdomains.

Backport of a3372f67cb from master
[1.5.x] Fixed #21212 -- Documented the reverse name for OneToOneField.

Thanks bjb at credil.org for the report.

Backport of f8632572ad from master
[1.5.x] Fixed #21296 -- Added docs for PostgreSQL and unix domains sockets.

Backport of 1e39982b6e from master
[1.5.x] Fixed #21253 -- PBKDF2 with cached HMAC key

This gives a 2x speed increase compared to the existing implementation.

Thanks to Steve Thomas for the initial patch and Tim Graham for finishing it.

Backport of 1e4f53a6eb8d1816e51eb8bd8f95e704f6b89ead from master.