core, core/vm: implemented a generic environment (#3348)

Environment is now a struct (not an interface). This
reduces a lot of tech-debt throughout the codebase where a virtual
machine environment had to be implemented in order to test or run it.

The new environment is suitable to be used en the json tests, core
consensus and light client.

core/state_processor.go

@@ -96,28 +96,36 @@ func ApplyTransaction(config *params.ChainConfig, bc *BlockChain, gp *GasPool, s
 	if err != nil {
 		return nil, nil, nil, err
 	}
-
-	_, gas, err := ApplyMessage(NewEnv(statedb, config, bc, msg, header, cfg), msg, gp)
+	// Create a new context to be used in the EVM environment
+	context := NewEVMContext(msg, header, bc)
+	// Create a new environment which holds all relevant information
+	// about the transaction and calling mechanisms.
+	vmenv := vm.NewEnvironment(context, statedb, config, vm.Config{})
+	// Apply the transaction to the current state (included in the env)
+	_, gas, err := ApplyMessage(vmenv, msg, gp)
 	if err != nil {
 		return nil, nil, nil, err
 	}
 
 	// Update the state with pending changes
 	usedGas.Add(usedGas, gas)
+	// Create a new receipt for the transaction, storing the intermediate root and gas used by the tx
+	// based on the eip phase, we're passing wether the root touch-delete accounts.
 	receipt := types.NewReceipt(statedb.IntermediateRoot(config.IsEIP158(header.Number)).Bytes(), usedGas)
 	receipt.TxHash = tx.Hash()
 	receipt.GasUsed = new(big.Int).Set(gas)
-	if MessageCreatesContract(msg) {
-		receipt.ContractAddress = crypto.CreateAddress(msg.From(), tx.Nonce())
+	// if the transaction created a contract, store the creation address in the receipt.
+	if msg.To() == nil {
+		receipt.ContractAddress = crypto.CreateAddress(vmenv.Context.Origin, tx.Nonce())
 	}
 
-	logs := statedb.GetLogs(tx.Hash())
-	receipt.Logs = logs
+	// Set the receipt logs and create a bloom for filtering
+	receipt.Logs = statedb.GetLogs(tx.Hash())
 	receipt.Bloom = types.CreateBloom(types.Receipts{receipt})
 
 	glog.V(logger.Debug).Infoln(receipt)
 
-	return receipt, logs, gas, err
+	return receipt, receipt.Logs, gas, err
 }
 
 // AccumulateRewards credits the coinbase of the given block with the