build/manage_offer.go
func UpdateOffer(rate Rate, amount Amount, offerID OfferID) (result ManageOfferBuilder) {
	return ManageOffer(false, rate, amount, offerID)
}
func UpdateOffer(rate Rate, amount Amount, offerID OfferID) (result ManageOfferBuilder) {
	return ManageOffer(false, rate, amount, offerID)
}
// UpdateOffer updates an existing offer