Refs #17262.

This commit deprecates django.utils.tzinfo in favor of the more recent
django.utils.timezone which was introduced when Django gained support
for time zones.

* override_settings may now be imported from django.test
* removed Approximate from django.test
* updated documentation for things importable from django.test

Thanks akaariai for the suggestion.

Thanks Aymeric for the suggestions.

refs #10164

Thanks Panagiotis Issaris for the report.

Thanks outofculture at gmail.com for the suggestion.

To enable testing on Oracle 12c

Passed large maxlinelen to email.Header to prevent newlines from being
inserted into value returned by _convert_to_charset

Thanks mjl at laubach.at for the report.

refs #21067

Thanks to robin for the report and claudep for the review.

Inputs acceptable to time.mktime are platform-dependent.

Thanks void for the report.

Thanks mattaustin for the report and Pablo Recio (pyriku) for the patch.

Thanks jcd.

adding myself to authors file

Alex requested I add myself in IRC, so I am.  =)

fixes #19988, allow html in ordinal for humanize

Thanks jafula for the suggestion.

Fixed #20836 -- Ensure that the ForeignKey's to_field attribute is properly considered by the admin's interface when creating related objects.
Many thanks to Collin Anderson for the report and patch and to Peter Sheats for the test.

Thanks mjtamlyn for the suggestion.

Thanks mitsuhiko for the report.

This commit just adds a test since the problem was fixed in 8aaca651.

Improved docs for `contrib.admin.options.ModelAdmin.response_*`

Added links to code references in the docs for `response_add`,
`response_change` and `response_delete`.