@Override
	public Parcelable onSaveInstanceState() {
		return adapter.onSaveInstanceState(super.onSaveInstanceState());
	}
Registers a OnItemClickListener for this listview which will
expand the item by default. Any other OnItemClickListener will be overriden.

To undo call setOnItemClickListener(null)

Important: This method call setOnItemClickListener, so the value will be reset
library/src/main/java/com/tjerkw/slideexpandable/library/SlideExpandableListView.java