Redeemer receives SOL

[ctapang]

In the Liquity system, redeemers have to "catch" the riskiest trove in order to redeem from it. In our system, the selection can be done from the sorted list of troves, and we can design it such that the redeemer comes to our system knowing only how much stable-token she wants to exchange for SOL. Our system then selects the riskiest trove to either partially or fully redeem. Even in the case of a full redemption, the borrower does not lose all her SOL. If the contents of the first trove is not enough, the system redeems the next trove in line, and so on.