HBS MPC Circuit

[Mikerah]

The following ideal functionality needs to be implemented in MP-SPDZ:
State:
* Secret shared: [PoolETH], [PoolTOK] total currency amounts
* Public value: (PoolETH / PoolTOK) current price
* Bids (processed in an epoch, say every hour):
Secret shared:
* [AmtETH](positive to buy, negative to sell)
* [MinPrice](slippage limit)
To process a batch of transactions:
* In secret shared fashion, process each bid and update [PoolETH] and [PoolTOK] accordingly, if the resulting price is within MinPrice.
* Each party receives output describing whether their bid was completed or not (or how much was completed).

There are also miscellaneous tasks regarding the handling of MP-SPDZ for which subsequent issues will be created.

[Mikerah]

@lilione finished this.