[1.6.x] Fixed #21284 -- Prevented KeyError swallowing in fetch_command

Thanks wildfire for the report.

Backport of 3514bcb251 from master.
[1.6.x] Fixed bug causing CSRF token not to rotate on login.

Thanks Gavin McQuillan for the report.

Backport of ac4fec5ca2 from master
[1.6.x] Fixed ReST error in 1.6. release notes.

Backport of 651bb73ab3 from master
[1.6.x] Added a warning regarding session security and subdomains.

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

Thanks bjb at credil.org for the report.

Backport of f8632572ad from master
[1.6.x] Cleaned formatting/comments in PasswordResetFormTest

Backport of 59a880863 from master.
[1.6.x] Fixed #21291 -- Ensured inactive users cannot reset their passwords

Thanks kz26 for the report and the suggested fix. Refs #19758.

Backport of 5f5259036 from master.
[1.6.x] Fixed #21296 -- Added docs for PostgreSQL and unix domains sockets.

Backport of 1e39982b6e from master
[1.6.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.
[1.6.x] Force update of the password on iteration count changes.

Backport of 7d0d0dbf26a3c0d16e9c2b930fd6d7b89f215946 from master.
[1.6.x] Added docs for the hasher's iteration count changes.

Backport of 28b70425afb2fb8bcbec09d249e37fa786f8a155 from master.
[1.6.x] Fixed #21249 -- variable name typo in compiler.get_grouping()

The typo could have consequences in exceptional cases, but I didn't
figure out a way to actually produce such a case, so not tests.

Report & patch by Michael Manfre.

Backport of 86c248aa64 from master
[1.6.x] Fixed an I18N test class tearDown method.

a3690168cb from master.
[1.6.x] Decode from UTF-8 explicitly when reading a text file in makemessages.

This shows itself with Python 3 under Windows where UTF-8 usually isn't
the default file I/O encoding and caused one failure and three errors
in our test suite under that platform setup.

b5f52647fe from master.
[1.6.x] Fixed #21304 -- Typo in docs/topics/testing/advanced.txt

Thanks joao at silvaneves.org for the report.

Backport of 9704c49d59 from master
[1.6.x] Added 1.5.5 and 1.4.9 release notes

Backport of 2eb8f15516 from master
[1.6.x] Fixed #21307 -- Moved TransRealMixin to django.test.utils.

51d2e1fb23 from master.
[1.6.x] Bump version number for 1.6 release candidate.
Fixed #13245: Explained Oracle's behavior w.r.t db_table
and how to prevent table-name truncation

Thanks russellm & timo for discussion, and timo for review.

Backported from master 317040a73b77be8f8210801793b2ce6d1a69301e
[1.6.x] Workaround admin scripts test failures on Windows+Python 3.

Change strategy used to examine instrumented output to acommodate the
fact that on Windows, where the path separator is '\', repr() of Python
modules has changed in Python 3 to use escaped backslashes in the FS
path section (e.g.
'C:\\python3x\\Lib\\site-packages\\django\\contrib\\auth\\models.py')
without having to special-case based on platform.

c04f3fc686 from master.