Alpha update #2: your saved missions come back

- Loading a save made during a mission (tutorial or campaign) lost the mission itself: no objectives panel, no trophy, no next mission. Fixed. The tutorial now resumes at the step you saved on.
- Saves made before this update stay as sandbox games, sorry about that: start the mission again if you were in one.
- Room names now show in English ("Outdoor games 1" instead of "Jeux extérieurs 1").