Multiple sends

This is a suggestion about how to allow multiple currency-send operations to take place within a single MasterCoin transaction, and allow the currency to be sent to any transaction output specified by index, rather than only to the "reference address".

The goal here is to enable multiple currency send operations to take place within a single MasterCoin transaction. From the commentary on the proposed change:

"One common use case is to send units of several different currencies simultaneously to the same address. Another common use case is to distribute funds to multiple recipients from a single input."

My underlying thinking is that as the volume of transactions on the bitcoin network grows, the day may soon come when transactions need to have significant fees attached in order to complete for inclusion in the blockchain. So it makes sense to look for ways to enable multiple related operations to be performed in a single transaction, rather than lots of individual ones. That will be cheaper for the user.

Gideon