Add Assets/Scripts/Dpr/Box SaveBoxData.cs contents

Hey,

So you've marked Assets/Scripts/Dpr/Box/SaveBoxData.cs TODO and I'm currently writing a script and you filling that file would really help me. I can't go too much to the script, I will just say that it would be a masterpiece. No need to rush though, but I'm just saying it! Thanks for seeing this message.

Aleksander