This implements micropayment payment channels in several parts:
* Adds PaymentChannel[Server|Client]State state machines which
handle initialization of the payment channel, keep track of
basic in-memory state, and check data received from the other
side, based on Mike Hearn's initial implementation.
* StoredPaymentChannel[Client|Server]States manage channel
timeout+broadcasting of relevant transactions at that time,
keeping track of state objects which allow for channel
resume, and are saved/loaded as a WalletExtension.
* Adds PaymentChannel[Client|Server] which manage a connection
by getting new protobufs, generating protobufs for the other
side, properly stepping the associated State object and
ensuring the StoredStates object is properly used to save
state in the wallet.
* Adds PaymentChannel[ClientConnection|ServerListener] which
create TCP sockets to each other and use
PaymentChannel[Client|Server] objects to create/use payment
channels.
The algorithm implemented is the one described at
https://en.bitcoin.it/wiki/Contracts#Example_7:_Rapidly-adjusted_.28micro.29payments_to_a_pre-determined_party
with a slight tweak to use looser SIGHASH flags so that the
Wallet.completeTx code can work its magic by adding more inputs if
it saves on fees.
Thanks to Mike Hearn for the initial state machine implementations
and all his contracts work and Jeremy Spilman for suggesting the
protocol modification that works with non-standard nLockTime
Transactions.
This forms the base for payment channel network connections, with
a simple single-threaded server which accepts new connections, a
simple single-threaded client which makes a single connection to a
server, and a ProtobufParser which handles data generated by a
connection, splits them into Protobufs and provides a reasonable
interface to users who wish to create/accept protobuf-based
connections.
1) Switch the outpoint index field to be uint32 and fix isCoinBase() to consider the unsigned versions only. Resolves issue 420.
2) Regenerate the protobuf and fix an out of date definition in WalletProtobufSerializer that it exposed.
and looks like a broken attempt to implement file locking. Neither
store that tried to use it is supporte anymore so don't bother replacing
with real file locks.
Add a method for signing a given input and use it.
Convert some code that was working with raw bytes to use TransactionSignature.
Rename Transaction.hashTransactionForSignature to just hashForSignature.
General API tweaks and cleanups.
