[Pharo-project] NativeBoost label call

Hi Igor, I need support to call labels in Waterfall. I used to have a changeset with this changes. But now i want to put Waterfall on Jenkins. So it would be easier if NB already has the implementation. Otherwise i would need to load a changeset after loading WF code through Metacello. I attach you my changes so you can check if you want to integrate them. If you prefer not to integrate them just tell me so i check for the other solution. Cheers, Guido.