Fixed #21560 -- missing 'slug' field in example code
I updated the documentation, that the modelform now includes the 'slug' field.
Merge pull request #2058 from c-schmitt/fixes_21560

Fixed #21560 -- missing 'slug' field in example code
Fixed E124 pep8 warnings.
Moved imports to the top of the defaultfilters module.
Fix sqlmigrate's output for parameters
Change FKs when what they point to changes
Better default name for migrations we can't give nice names to
Fix altering of SERIAL columns and InnoDB being picky about FK changes
Fixed #21510 -- Readded search reset link in changelist search bar

Thanks moritz.pfeiffer at alp-phone.ch for the report and
Tim Graham for the initial patch.
Fixed #21563 -- Single related object descriptors should work with `hasattr`.

Thanks to Aymeric Augustin for the review and Trac alias monkut for the report.
Fixed #21462 -- Made `assertNumQueries` print executed queries on failure.
Fixed #13165 -- Display edit and delete links for admin related fields.