Draft PR for review : Add physics module to Nazara (physics engine: nphysics2d)

[Faymoon]

[alexandre-janniaux]

You can probably set a correct naming and description of what you're adding with this PR. ;)

Btw, github has a dedicated concept for draft PR, you can check all this here: https://github.blog/2019-02-14-introducing-draft-pull-requests/