Fixed #21558 -- Support building CHM files.

Thanks Michał Pasternak.
Migration VCS conflict detection and --merge for makemigrations
List 1.6.x releases in descending order
Merge pull request #2029 from alasdairnicol/releases_ordering

List ed 1.6.x releases in descending order
Fixing manager documentation inaccuracy
Removed 'return' in __init__
Merge pull request #2030 from frankwiles/master

Fixed manager documentation inaccuracy
Fixed a flake8 error
Fix poor variable name (flake8 warning)
Better error reporting when from_app_cache fails
Corrected setting name in gis test error message.
Fixed typo in custom model field documentation.
Fixed another typo in custom model field documentation.
Fixed TypeError when rendering ModelState with multiple bases.
Fixed #21562 -- Warned against using the same app name as a django contrib app.

Thanks yourcelf for the report.
Removed unreachable `else` in `try` block.
Renamed syncdb to migrate in spatialite backend
Fixed #19678 -- GeoDjango test failure with spatialite >= 3.0.

Thanks Julien for the report and Claude for the fix.
Merge pull request #2037 from bmispelon/invalidbaseserror

Fixed TypeError when rendering ModelState with multiple bases.
Added app_label to the error message when field reconstructing fails.