- Added for Planet 2 / UpsideDown Planet a themed audio

- Fixed bug that the camera not return to player after switch and show Planet 2

- Updateted gravity method inside Planet 1 / Ice Planet. Inside the planet during the 2D Passage the gravity will now be much stable and  smoother. 

- Added low gravity on Planet 3 for fun. Just because the planet is only there for decoration.

- Added invisible walls so the player cant go out of bounds on the startplanet.