EditRelationMixIn: stop using user_rql_callback
Add generic add_relation/delete_relation ajax functions and use those.
Related to #3567793
#! /bin/sh -e#if [ "$1" = configure ]; then if which install-docs >/dev/null 2>&1; then install-docs -i /usr/share/doc-base/cubicweb-doc fifi#DEBHELPER#exit 0