Fixed ImportError when running contrib.gis tests without libgeos installed.
Revert "Fixed #20296 -- Allowed SafeData and EscapeData to be lazy"

This reverts commit 2ee447fb5f8974b432d3dd421af9a242215aea44.

That commit introduced a regression (#21882) and didn't really
do what it was supposed to: while it did delay the evaluation
of lazy objects passed to mark_safe(), they weren't actually
marked as such so they could end up being escaped twice.

Refs #21882.
Added previous commit to 1.6.2 release notes.
Removed import which is now unused
Extended the release notes for chainable Manager/QuerySet methods.

Refs #20625.
Added missing items to 1.6.2 release notes.
Fixed #21731 -- Made javascript_quote escapes '</'.
Fixed #17005 -- Added CurrentSiteMiddleware to set the current site on each request.

Thanks jordan at aace.org for the suggestion.
Fixed #17713 -- Renamed BaseDatabaseFeatures.allows_primary_key_0 to allows_auto_pk_0.

MySQL does allow primary key with value 0. It only forbids autoincrement
primary key with value 0.

Thanks Claude Paroz for the report.
Updated 1.6.2 release notes for release (and linkified tickets).
Bumped version number for 1.7a2
Fixed 16192 -- Made unique error messages in ModelForm customizable.

Overriding the error messages now works for both unique fields, unique_together
and unique_for_date.

This patch changed the overriding logic to allow customizing NON_FIELD_ERRORS
since previously only fields' errors were customizable.

Refs #20199.