Health, Toggle and Scenes polishment

- Polished the code;
- Healthbar change of HPs is now managed with a Coroutine so that it is much smoother and pleasant to see;
- Added customizable Player Pref  to better manage the workflow in the slider script;
- Added custom KeyCode to the toggle script so you can mute the audio from the keyboad;
- Scenes were improved.

For now this is all!

if you have any reccomendation please leave a comment :)