Added collection.move(fromIndex: number, toIndex: number) which calls items.move on the inner Observable Array
parsing a 3+ level deep parent->child->parent structure no longer results in duplicate models. This works by checking the collection after parsing to see if a model with the same ID was added to the collection. If it was, parse the data again but while updating the existing model. Refer to the README for an example.
Calling collection.get(undefined) no longer errors when passed null or undefined.