[1.7.x] Fixed #22511 -- Added args to migrations management commands.

Backport of 83413c53d2 from master
[1.7.x] Removed unused import.

Backport of d9c272b22f from master
[1.7.x] Fixed #22442 -- Provided additional documentation regarding id fields clashing.

Thanks benjaoming for raising the issue and Loic for the examples.

Backport of 8ec388a69d from master
[1.7.x] Fixed #22537 -- Add tests and improved docs for field subclass with choices.

Backport of 7fd1b35ed7 from master
[1.7.x] Fixed #22474 -- Made migration recorder aware of multiple databases

Thanks Tim Graham for the review.
Backport of 7c54f8cce from master.
[1.7.x] Fixed #19195 -- Allow explicit ordering by a relation `_id` field.

Thanks to chrisedgemon for the report and shaib, akaariai and
timgraham for the review.

Backport of 24ec9538b7 from master
[1.7.x] Fixed #22485: Include all unmigrated apps in project state by default.
[1.7.x] Fixed #22546 -- Removed idioms in tutorial 2.

Thanks bjb at sourcerer.ca for the suggestion.

Backport of 927245ccd8 from master
[1.7.x] Cleanup failing test w/contenttypes and remove useless graph load
[1.7.x] Fixed #22547 -- Added some links to tutorial 2.

Thanks bjb at sourcer.ca for the suggestion.

Backport of b0d032f9fc from master
[1.7.x] flake8 fixes.

Backport of 45c2d1f5d9 from master.
[1.7.x] Fixed #22539 -- Copied exclude argument in Model.full_clean() to prevent side effects.

Backport of e2e4cdba11 from master
[1.7.x] Fixed #22551 -- Made oracle backend method Python 3 compatible

Thanks fatal10110 at gmail.com for the report. The fix is 1.6-only
because that code has been refactored in 1.7 (6983201cfb).
'Docs-only' forward port of 120a98120 from 1.6.x.
[1.7.x] Fix migration autodector to work correctly with custom deconstructed values
[1.7.x] Fixed #22558 -- Added missing word in contributing docs

Backport of c8d257e81 from master.
[1.7.x] Fixed #22565 -- Prevented pgettext_lazy crash with bytestring input

Thanks ygbo for the report.
Backport of 142c27218 from master.