Secret new game mechanic

Change List:
- New puzzle to solve to reveal a new game mechanic.
- New map to discover.
- Improved physics stability.
- Added a keymapping list that you can show by pressing the TAB key.
- Added a graphic settings menu. You can open it by pressing the F1 key.
- Added a slider in the graphic settings menu to control the Motion Blur amount.
- Much more to discover... <3