Sandbox editor for JMonkeyEngine

@david.bernard.31 said: today I give a second try. And I'll create github's issues about my feedback (as you asked). You did a big work, and it'll be a shame if you're the only one to use it, so I hope my github's issue will help.

Thank you, I’ll try to make a 0.0.2 version over the weekend to fix some small issues, maybe wait till then ?