* Removed some strange code that didn't apply state reverting properly
* Refactored code setting from vm & state transition to the executioner
* Updated tests
* change gas cost for contract creating txs
* invalidate signature with s value greater than secp256k1 N / 2
* OOG contract creation if not enough gas to store code
* new difficulty adjustment algorithm
* new DELEGATECALL op code
Added a `Difference` method to `types.Transactions` which sets the
receiver to the difference of a to b (NOTE: not a **and** b).
Transaction pool subscribes to RemovedTransactionEvent adding back to
those potential missing from the chain.
When a chain re-org occurs remove any transactions that were removed
from the canonical chain during the re-org as well as the receipts that
were generated in the process.
Closes#1746
When the transaction state recovery kicked in it assigned the last
(incorrect) nonce to the pending state which caused transactions with
the same nonce to occur.
Added test for nonce recovery
Changed the transaction pool to listen for ChainHeadEvent when resetting
the state instead of ChainEvent. It makes very little sense to burst
through transactions while we are catching up (e.g., have more than one
block to process)
Removed the managed tx state from the chain manager to the transaction
pool where it's much easier to keep track of nonces (and manage them).
The transaction pool now also uses the queue and pending txs differently
where queued txs are now moved over to the pending queue (i.e. txs ready
for processing and propagation).
* Changed CalcGasLimit to no longer need current block
* Added a gas * price + value on tx validation
* Transactions in the pool are now re-validated once every X
Transactions are now propagated to peers from which we have not yet
received the transaction. This will significantly reduce the chatter on
the network.
Moved new mined block handler to the protocol handler and moved
transaction handling to protocol handler.