Generic elements deletion through queryset

arkindex/documents/apps.py

arkindex/documents/managers.py

arkindex/documents/signals.py

arkindex/documents/tasks.py

arkindex/documents/tests/test_destroy_elements.py

arkindex/sql_validation/corpus_delete.sql

arkindex/sql_validation/element_trash_children.sql

arkindex/sql_validation/element_trash_deep.sql

arkindex/sql_validation/element_trash_ml_class.sql

arkindex/sql_validation/element_trash_no_children.sql