Refactored VM to two separate VMs; std & debug

Standard VM should be about 10x faster than the debug VM. Some error
checking has been removed, all of the log statements and therefor quite
some unnecessary if-statements.

ethvm/environment.go

@@ -0,0 +1,26 @@
+package ethvm
+
+import (
+	"math/big"
+
+	"github.com/ethereum/eth-go/ethstate"
+	"github.com/ethereum/eth-go/ethutil"
+)
+
+type Environment interface {
+	State() *ethstate.State
+
+	Origin() []byte
+	BlockNumber() *big.Int
+	PrevHash() []byte
+	Coinbase() []byte
+	Time() int64
+	Difficulty() *big.Int
+	Value() *big.Int
+	BlockHash() []byte
+}
+
+type Object interface {
+	GetStorage(key *big.Int) *ethutil.Value
+	SetStorage(key *big.Int, value *ethutil.Value)
+}