[refactoring] introduce add_etype_button function to properly create button to add a new entity
also properly use cw_create_url to generate the URL to add the entity
#! /bin/sh -ecase "$1" in remove) if [ -x "/etc/init.d/cubicweb-ctl" ]; then invoke-rc.d cubicweb-ctl stop || true fi ;;esac#DEBHELPER#exit 0