Fixed #22306 -- Deprecated future versions of cycle and firstof template tags.
Fixed #22250 -- regression in gis compiler for non-concrete fields

Thanks to gwahl@fusionbox.com for the report.
Confirmed GEOS 3.4 support
Confirmed Spatialite 4 support
Added note in geo library docs
Dropped support for GEOS 3.1
Dropped support for GDAL 1.6
Removed unused imports.
Fixed #22329 -- Used label_tag() in some admin auth templates.

refs #17922.
Fixed #21858 -- Clarified 1.6 release note regarding M2M help text changes.

Thanks lee at semel.net for the report.
Unit testing Postgis version check

Refs #22334.
Skipped PostGIS version tests when psycopg2 not installed

Refs #22334. Thanks Tim Graham for spotting the issue.
Increased memoization cache size for language codes.

There may be more than 100 (default maxsize) commonly seen xx-yy values
on some sites. The additional memory consumption isn't significant.

Also added a comment explaining why this cache must have a maxsize.
Cleaned up tests for multiple databases.
Fixed transaction handling for a number of operations on related objects.

Thanks Anssi and Aymeric for the reviews. Refs #21174.
Merge pull request #2489 from loic/related_transactions

Fixed transaction handling for a number of operations on related objects.
Fixed #19816 -- Pre-evaluate querysets used in direct relation assignments.

Since assignments on M2M or reverse FK descriptors is composed of a `clear()`,
followed by an `add()`, `clear()` could potentially affect the value of the
assigned queryset before the `add()` step; pre-evaluating it solves the problem.

This patch fixes the issue for ForeignRelatedObjectsDescriptor,
ManyRelatedObjectsDescriptor, and ReverseGenericRelatedObjectsDescriptor.
It completes 6cb6e1 which addressed ReverseManyRelatedObjectsDescriptor.
Merge pull request #2487 from loic/ticket19816

Fixed #19816 -- Pre-evaluate querysets used in direct relation assignments.
Fixed mistake in tests from commit 2039908. Refs #19816.
Merge pull request #2495 from loic/ticket19816

Fixed mistake in tests from commit 2039908. Refs #19816.