[storage] relies on event=='deleted' to detect "delete" event When we delete a previously edited entity, it *will* have a cw_edited attribute even if the goal is to delete it. The function get an argument that explicitly contains the "delete" event. The code now uses that instead.

doc/book usr/share/doc/cubicweb-documentation
doc/html usr/share/doc/cubicweb-documentation
debian/cubicweb-doc usr/share/doc-base/cubicweb-doc