Fix VM memory allocation optimizations by reducing what we allocate on the heap

internal/object/null.go

@@ -2,28 +2,28 @@ package object
 
 type Null struct{}
 
-func (n *Null) Bool() bool {
+func (n Null) Bool() bool {
 	return false
 }
 
-func (n *Null) Type() Type {
+func (n Null) Type() Type {
 	return NullType
 }
 
-func (n *Null) Inspect() string {
+func (n Null) Inspect() string {
 	return "null"
 }
 
-func (n *Null) String() string {
+func (n Null) String() string {
 	return n.Inspect()
 }
 
-func (n *Null) LogicalNot() Object {
-	return &Boolean{!n.Bool()}
+func (n Null) LogicalNot() Object {
+	return Boolean{!n.Bool()}
 }
 
-func (n *Null) Compare(other Object) int {
-	if _, ok := other.(*Null); ok {
+func (n Null) Compare(other Object) int {
+	if _, ok := other.(Null); ok {
 		return 0
 	}
 	return 1