Add transaction type Multi Send

List of additions:

* Added a boolean array data type, to allow true/false flags.
* Added transaction type 5, Multi Send, a method of sending one or more types of coins to one or more recipients.

This pull request primarily intends to increase the mobility of Mastercoin and derivative coins/tokens. The current standard method of transfer is the Simple Send transaction type. The throughput of the Simple Send is limited to a single type of coin/token being send to a single recipient. The addition of the Multi Send transaction type would enable one or more recipients to receive one or more types of coins/tokens in a single Master Protocol transaction.

This pull request is a "duplicate" of https://github.com/mastercoin-MSC/spec/pull/199. Please excuse the clutter - I'm still learning to use GitHub.