ROME — On the eve of a trip to the United States, Pope Francis has called himself a “son of immigrants” and confirmed the point by issuing a blunt warning to any religious orders in Europe that spurn his recent call to open their doors to refugees because they want to make money off their properties instead. Go ahead, the pope said, but be ready to pay taxes just like everybody else. “Some religious orders say ‘No, now that the convent is empty we are going to make a hotel and we can have guests, and support ourselves that way,...