v4.0.3

# 4.0.3 __fixed__ - Fixed `TransactionBuilder` to require that the Transaction has outputs before signing (#1151) - Fixed `payments.p2sh`, which now takes the network from the redeem attribute if one is not given in the object argument (#1232) - Fixed `Block.calculateTarget` to allow for exponents up to 29 (#1285) - Fixed some low priority rarely occurring bugs with multisig payments and `TransactionBuilder` multisig processing (#1307) __added__ - Regtest network object to `networks` (#1261)