wrap long words in field labels on admin forms, closes #18755

Otherwise, words overlap into the fields themselves, which makes the labels
unreadable.
Fixed #19690 - Removed unused import
Removed an import of a class unused in the Ajax example.
Attempted to reduce version mismatch problems in the tutorial.
Fixed #19692 -- Completed deprecation of mimetype in favor of content_type.

Thanks Tim for the report and initial patch.
Fixed #19708 -- Exception in timezone.override(None).

Thanks rafales.
Deprecated undocumented warnings manipulation testing tools.
Fixed #19711 -- Typo in __all__ declaration in django/test/simple.py
Merge pull request #690 from rafales/ticket_19711

Fixed #19711 -- Typo in django.test.simple.__all__
Added introspection tests for most of Django model fields
Fixed #19709 -- Fixed TimeField introspection on MySQL

Thanks Eugene Grachev for the report.
Fixed #19341 -- Detected NullBooleanField when introspecting models

Thanks Tim Bowden for the report.
Fixed dict randomization issue in inspectdb
Renamed inspectdb field names for clarity
Set bigger maxDiff for ogrinspect tests
Fixed #19714 -- Updated documentation about TemplateView context

Thanks Aramgutang for the report. Refs #17228.
Fixed #19715 -- Simplified findstatic output when verbosity set to 0
Documented ArchiveIndexView's date_list context variable.

Refs #16218.
Added myself to core developpers
Merge pull request #334 from dlo/tickets/18755

Fixed #18755 -- Wrapped long admin forms fields labels.
Fix rst syntax error.

Thanks Chris Rebert for the report.