Incompatible file storage

This app's usage of files is incompatible with the Django storage API and the core's support for arbitrary storage backend.

The function path_and_rename is eing removed from core.

added part::backend type::bug labels

@fph @hansegucker Please fix this quickly. I will drop path_and_rename from Core before the end of the current sprint (provided that no official apps depend on it).

assigned to @nik

assigned to @fph and unassigned @nik

changed due date to April 15, 2021

mentioned in merge request !14 (merged)

closed with commit f75031e3

unassigned @fph