Super jump and slippery items fix

This update fixes two minor but annoying bugs found by Laura (Hello Laura! And thank you a lot for telling us about these issues, even though we know there's one you are keeping for yourself because you think it makes the game easier) :D

• Players won't super-jump out of ladders anymore. If you stunned a rat while climbing down a ladder and then climbed up, you experienced an extra push that could make the player get to the platform above. Useful, but unexpected.

• If you are carrying an item and you collide with a rat, the item flies away. It was impossible to pick it up again unless you walked away and then back to it.

Thank you for playing! See you soon!