Added a new monster and fixed some bugs.

- Addition of a monster: the mimic chest.

- There is even more chance of getting a missing item when opening a chest.

- The spider web is more visible in the bathroom.

- Spiders are now targeted by the insecticide.

- Fixed a case where the red circles appeared when finishing a category using a tool.

- Fixed a few cases where the move count could be bad at the end.

- Made more robust the save after receiving the reward in the win menu.