parmas, crypto, core, core/vm: homestead consensus protocol changes

* 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

core/vm/contracts.go

@@ -93,7 +93,8 @@ func ecrecoverFunc(in []byte) []byte {
 	vbig := common.Bytes2Big(in[32:64])
 	v := byte(vbig.Uint64())
 
-	if !crypto.ValidateSignatureValues(v, r, s) {
+	// tighter sig s values in homestead only apply to tx sigs
+	if !crypto.ValidateSignatureValues(v, r, s, false) {
 		glog.V(logger.Debug).Infof("EC RECOVER FAIL: v, r or s value invalid")
 		return nil
 	}