_pkg.dev: drop useless mgetdata from payload

_pkg.dev/wire/payload/mgetdata.go

@@ -1,18 +0,0 @@
-package payload
-
-import (
-	"github.com/CityOfZion/neo-go/pkg/wire/command"
-)
-
-// GetDataMessage represents a GetData message on the neo-network
-type GetDataMessage struct {
-	*InvMessage
-}
-
-//NewGetDataMessage returns a GetDataMessage object
-func NewGetDataMessage(typ InvType) (*GetDataMessage, error) {
-	getData, err := newAbstractInv(typ, command.GetData)
-	return &GetDataMessage{
-		getData,
-	}, err
-}

_pkg.dev/wire/payload/mgetdata_test.go

@@ -1,19 +0,0 @@
-package payload
-
-import (
-	"testing"
-
-	"github.com/CityOfZion/neo-go/pkg/wire/command"
-	"github.com/stretchr/testify/assert"
-)
-
-func TestGetDataCommandType(t *testing.T) {
-	getData, err := NewGetDataMessage(InvTypeBlock)
-
-	assert.Equal(t, err, nil)
-	assert.Equal(t, command.GetData, getData.Command())
-}
-
-func TestOtherFunctions(t *testing.T) {
-	// Other capabilities are tested in the inherited struct
-}