ListTransactionsOfBlock RPC method

The method 'listtransactionsofblock' lists all transactions (from the wallet) which are in block with blockhash <hash>

It can be used this way: (pseudo-code)
```
ScanTransactions() {
  Database.TransactionBegin()

  long lastBlock = BitcoinRPC.getLastBlockNr()
  long lastScannedBlock = Database.getLastScannedBlock()

  while (lastBlock - lastScannedBlock > targetConfirms)  {
    lastScannedBlock++;
    string hash = BitcoinRPC.getHashOfBlock(lastScannedBlock)
    list<Transaction> list = BitcoinRPC.getTransactionsOfBlock(hash)
    for (Transaction t : list)
    {
      // do something
      // at this point, you can absolutely be sure to see only transactions 
      // with <targetconfirms> confirms.
      // and you only have to scan each block exactly once
    }
  }
  Database.saveLastScannedBlock()
  Database.TransactionCommit()
}
```
This is an easy example how payments can reliably be received.



Explained here: https://github.com/bitcoin/bitcoin/issues/2565