Feature Request: SMT-to-SMT conversion set by operators

[clayop]

Related to issue #168 , but while the previous issue suggested vertical structure, this suggestion is more like to be horizontal.

1. An operator can set conversion rate of his SMT (SMT1) with other SMT (SMT2). Let's say SMT1 = 2 * SMT2, so the ratio is 2.
2. This is unidirectional. Only SMT2 holders can convert to SMT1.
3. There is conversion pool and the maximum conversion is limited by the pool size. The pool can be refilled by the SMT operator.

For example. Assuming there are two IOUs created as SMT. BIGMAC and SUSD. BIGMAC operator wants to sell BIGMAC to SUSD users, so he set the ratio 2 (1 BIGMAC = 2 SUSD). And he filled the conversion pool with 10,000 BIGMAC. Now, SUSD users can buy BIGMAC using conversion.

This can address the following problems with using AMM

1. Given STEEM price volatility, IOU operators need to accurately track their IOU prices in STEEM. If not, there can be risks. For instance, while STEEM price drops 20% but IOU/STEEM price keeps the same, IOU operators will lose 20% per sold.
2. Using two AMMs (SUSD->STEEM, STEEM->BIGMAC) requires to pass two spreads, which in turn a loss.

To avoid having infinite markets, the number of conversion ratio can be limited. If the limitation is 3, BIGMAC operators can have BIGMAC-SUSD, BIGMAC-SCNY, and BIGMAC-SKRW. If we need additional anti-abusing tool, locking-in STEEM per conversion ratio can be used.

[clayop]

I should have added that the ratio can be re-defined by the operator.