TxBuilder: add failing test for non-zero vin inputs
TxBuilder: fix invalid txin.index usage for non-zero vin inputs
TxBuilder: avoid unnecessary recalculation of prevOutScript data
Transaction: throw if sequence is not a number
TxBuilder: add test for missing redeemScript if P2SH
TxBuilder: limit signatures depending on scriptType
scripts: add error for >n signatures with multisig
TxBuilder: add more failing cases and error handling
Merge pull request #270 from dcousens/txfix

TransactionBuilder to correctly handle non-zero vin in inputs