This is a big change that also many general fixes to problems found
when creating transactions. In particular the Utxo and Tx formats and
serialization functions were updated with additional information that
would be necessary for rolling back old utxo and tx data data after
btcd chain switches. This change also implements the json methods
'sendfrom' and 'sendmany' to create a new transaction based on a
frontend request.
Transactions are currently not sent to btcd since the tx relay code is
not finished yet, so a temporary error is returned back to frontends
who try to send new transactions.
btcd was changed to send the block hash for new block notifications as
a big endian string, so type assert as a string and convert to a
btcwire.ShaHash.
Each wallet needs its own handler running and listening to replies
from btcd, so that wallet can be synced to disk with the new tx or
utxo information. Another rounter to map from addresses to wallets
could have been written, but we'll use the JSON Id router message
router instead.
