Updates to BabylonJS' latest version (8.8.2)

(Called this version 4.0 due to babylon update alongside first official AR version.)

Updated

• Moved onto version 8.8.2 of babylonjs.

Added

• Implemented the XR options needed for a proper AR experience.

Changed

• Skybox must now be bigger than the habitable zone.
• Updated README according to current launching process.

Fixed

• Trajectory lines are unaffected by ambiant light to fix rendering issues.
• Animation times now depend on the correct values.

Issues

• Skybox is disabled.