ROOM_I_NO_ALLOW_STEED   This room doesn't allow any steeds inside if the
                        return value is 1.
                        By default steeds are prohibited from going to
                        rooms that have this property or the
                        ROOM_I_INSIDE property.
                        See /d/Genesis/steed.c for the handling of illegal
                        and legal destination rooms of the steeds.
