ListSet (collection.immutable.ListSet) is a inverse ordered set. I need ordered set. This is a example of original ListSet:

```
var a = ListSet(1,2,3)
var ite = a.iterator
ite.next // returns 3
ite.next // returns 2
ite.next // returns 1

```

And this is a example of I need:

```
var a = ListSet(1,2,3)
var ite = a.iterator
ite.next // returns 1
ite.next // returns 2
ite.next // returns 3

```

UPDATE:

"Ordered" is a "Insertion Ordered" for me. I need this:

```
var a = ListSet(1,2,3)
a += 5
a += 4
var ite = a.iterator
ite.next // returns 1
ite.next // returns 2
ite.next // returns 3
ite.next // returns 5
ite.next // returns 4

```