Fixed #22030 -- Don't assume that all fields have a swappable_setting attribute.
Removed _actions_icnt declaration from local scope in admin JS.

Commit 4523fcd introduces _actions_icnt to the local scope,
which overrides the value set in the HTML.

The admin would incorrectly show selected rows in a change list
as "1 of undefined selected".
Updated docs that misreported django.apps.apps.ready as being a method.
Fixed #21654 -- Documented a use-case for Form.errors.as_data().

Thanks selwin for the suggestion.
Added missing snippet to show filename in docs
Fixed #21177 -- Made resolve_url support relative URLs.

This fixes redirecting to relative URLs with django.shortcuts.redirect.
Fixed #17942 -- Added a JsonResponse class to more easily create JSON encoded responses.

Thanks leahculver for the suggestion and Erik Romijn,
Simon Charette, and Marc Tamlyn for the reviews.
Fixed #21924 -- Added the ability to specify a reverse order for admin_order_field.

Thanks Klemens Mantzos for the report and initial patch.
Fixed #22035 -- reordered migration operations

Now AddField actions appear in operations list before AlterUniqueTogether
actions.

Thanks to SmileyChris for the report.
Added 1.6.3 release note for refs #21566.
Fixed #22049 -- Corrected a misspelling of dimensional
Change analyse (British) to analyze (American).
Fixed #22052 -- Corrected a misspelling of ellipsoid
Merge pull request #2281 from rhcarvalho/ticket_22053

Change analyse (British) to analyze (American).
Fixed typo in docstring.
Moved relative URL handling added in refs #21177 to a better place.

Thanks apollo13: "reverse() shouldn't know about absolute/relative paths."
Fixed typo in test docstring.
Fixed #22018 -- Fixed checks for ModelAdmin.fields not handling sub-lists.

Flatten a level of sublists before checking for duplicate fields.

When given sublists such as:

```python

class FooAdmin(admin.ModelAdmin):
    fields = ('one', ('one', 'two'))
```

The previous code did not correctly detect the duplicated 'one' field.

Thanks to jwa for the report.
Fixed typo in comment.
Fixed two typos.