Smartcontract (#39)

* deleted transfer_output added asset type and transaction result to core

* removed writing 0x00 when buffer length is 0

* Refactored emit into VM package + moved tx to own package.

* implemented transaction along with claimTransaction.

* refactored naming of transaction + added decode address for uint160 types

* removed unnecessary folder and files.

* transaction/smartcontract logic

* bumped version 0.24.0

pkg/smartcontract/param_context.go

@@ -0,0 +1,52 @@
+package smartcontract
+
+import "github.com/anthdm/neo-go/pkg/util"
+
+// ParamType represent the Type of the contract parameter
+type ParamType int
+
+// A list of supported smart contract parameter types.
+const (
+	SignatureType ParamType = iota
+	BoolType
+	IntegerType
+	Hash160Type
+	Hash256Type
+	ByteArrayType
+	PublicKeyType
+	StringType
+	ArrayType
+)
+
+// Parameter represents a smart contract parameter.
+type Parameter struct {
+	// Type of the parameter
+	Type ParamType
+	// The actual value of the parameter.
+	Value interface{}
+}
+
+// NewParameter returns a Parameter with proper initialized Value
+// of the given ParamType.
+func NewParameter(t ParamType) Parameter {
+	return Parameter{
+		Type:  t,
+		Value: nil,
+	}
+}
+
+// ContextItem represents a transaction context item.
+type ContextItem struct {
+	Script     util.Uint160
+	Parameters []Parameter
+	Signatures []Signature
+}
+
+// Signature represents a transaction signature.
+type Signature struct {
+	Data      []byte
+	PublicKey []byte
+}
+
+// ParameterContext holds the parameter context.
+type ParameterContext struct{}