[btcsuite/btcd] 506fc9: rpcserver: Allow tx result creation without block.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/btcsuite/btcd
  Commit: 506fc9fb948801a768425b37d61b4441e1b58c47
      
https://github.com/btcsuite/btcd/commit/506fc9fb948801a768425b37d61b4441e1b58c47
  Author: Dave Collins <da...@conformal.com>
  Date:   2015-07-28 (Tue, 28 Jul 2015)

  Changed paths:
    M rpcserver.go
    M rpcwebsocket.go

  Log Message:
  -----------
  rpcserver: Allow tx result creation without block.

This commit modifies the createTxRawResult code path along with callers
to work with block headers as opposed to btcutil.Blocks.  This in turn
allows the code in handleGetRawTransaction and
handleSearchRawTransactions to perform a much cheaper block header load
as opposed to a full block load.

While here, also very slightly optimize the createVinList function to
avoid creating a util.Tx wrapper and to take advantage of the
btcutil.Amount type added after the function was originally written