add of rat entity and some fake mist to test

- If you push E you create the fake mist
- The player can't move, but the mist can
- If you push A, you destroy the mist, and you can move again

My wish is to make collide the mist and the rat, to make the mist
dissapear and the player taking control of the rat.

But i've got some problem with the colisions.