Advanced pending deprecation warnings.

Also added stacklevel argument, fixed #18127.
Removed versionadded/changed annotations dating back to 1.4.
Silenced warnings in the tests of deprecated features.
Merge pull request #609 from mitar/patch-3

Fixed typo in collectstatic output.
Merge pull request #595 from bmispelon/patch-1

Fixed a typo in WidthRatioNode.
Removed links to deprecated IGNORABLE_404_STARTS/ENDS settings.

refs #19516 and 641acf76e7
Made sure join_field is always available in .join()

Refs #19385
Moved join path generation to Field

Refs #19385
Added Query.join_parent_model()

This simplifies especially compiler.py a lot, where almost the same
code was repeated multiple times.

Refs #19385
Made use of PathInfo.direct flag in trim_joins

Refs #19385
Minor improvement to proxy model handling

Refs #19385
Fixed GIS regression in get_default_columns()

I changed the normal compiler's get_default_columns() but didn't change
the copy-pasted code in GIS compiler's get_default_columns().

Refs #19385
Added further flexibility to ModelAdmin for controlling post-save redirections.
Refs #19505.
Fixed #19537 -- Made CheckboxInput._has_changed handle 'False' string

Thanks dibrovsd@gmail.com for the report.
Fixed #16241 -- Ensured the WSGI iterable's close() is always called.

Thanks Graham Dumpleton for the report.
Fixed #19519 -- Fired request_finished in the WSGI iterable's close().
Fixed #19453 -- Ensured that the decorated function's arguments are obfuscated in the @sensitive_variables decorator's frame, in case the variables associated with those arguments were meant to be obfuscated from the decorated function's frame.
Thanks to vzima for the report.
Fixed #17078 -- Made shell use std IPython startup.

This allows for a behavior more in line with what is expected by Ipython
users, e.g. the user namespace is initialized from config files, startup
files.

Thanks Benjamin Ragan-Kelley from the IPython dev team for the patch.
Fixed #19519 again -- Regression in LiveServerTestCase after fd1279a4.
Fixed #19457 -- ImageField size detection failed for some files.

This was caused by PIL raising a zlib truncated stream error since we fed
the parser with chunks instead of the whole image.