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

Otherwise, words overlap into the fields themselves, which makes the labels
unreadable.
Fixed #6682 -- Made shell's REPL actually execute $PYTHONSTARTUP and `~/.pythonrc.py`.

Also:

* Added a ``--no-startup`` option to disable this behavior. Previous
  logic to try to execute the code in charge of this funcionality was
  flawed (it only tried to do so if the user asked for ipython/bpython
  and they weren't found)
* Expand ``~`` in PYTHONSTARTUP value.

Thanks hekevintran at gmail dot com  for the report and initial patch.

Refs #3381.
Fixed #19577 - Added HTML escaping to admin examples.

Thanks foo@ for the report and Florian Apolloner for the review.
Fixed #19665 -- Ensured proper stderr output for Command.run_from_argv

Thanks Stefan Koegl for the report and Simon Charette for the review.
Patch by Claude for #16084.
Added more shortcuts to i18n docs in index page.
Revert "Patch by Claude for #16084."

This reverts commit 2babab0bb351ff7a13fd23795f5e926a9bf95d22.
Moved has_changed logic from widget to form field

Refs #16612. Thanks Aymeric Augustin for the suggestion.
Fixed #18460 -- Fixed change detection of ReadOnlyPasswordHashField

Thanks jose.sanchez et ezeep.com for the report and Vladimir Ulupov
for the initial patch.
Used property decorators in django/forms.py
Fixed validation of email addresses when the local part contains an @.

See also BaseUserManager.normalize_email -- it uses rsplit.

Refs #4833.
Fixed #19540 -- Stopped using deprecated os.stat_float_times.
Fixed #19589 -- assertRegexpMatches is deprecated in Python 3.3.
Moved BooleanField 'required' validation in validate()
Fixed #17158 -- Used a non-ambiguous representation of SQL queries

when a correct representation cannot be obtained.
Fixed #18483 -- Marked hidden field error string for translation

Thanks Evil Clay for the report and Emil Stenstrom for the initial
patch.
Fixed #16123 -- Ensured strptime receive proper string type

strptime generates an UnicodeEncodeError when using a non-ascii
unicode string on Python 2.
Fixed two malformed links.
Fixed #19677 -- Introspection of recursive foreign keys under SQLite.

Thanks Simon Charette.
Fixed #19676 -- Supported 'self' foreign keys in inspectdb.

Thanks Georgy Kutsurua for the report and Simon Charette for the patch.