Close a CDP. Clear all debt, unlock all collateral and delete the record.
Collateral will be used to pay any outstanding debt at market rate. Remaining
collateral will be returned to the pool.
$ dai --cup=<id> shut
$ seth send "1383193339611678105810169541746055541819509028773" "shut(bytes32)" "<cup-id>"
shut(self, cup_id: int) -> Transact: