QoL improvements

Hello everyone,

a new version is online with some QoL improvements.

- A tutorial level has been added. As I'm working on balancing the game I added a tutorial level with some explanation of the game mechanics. In this level you will be also able to practice the movement and the grinding gameplay without taking damage and without having to face any enemies.

- Level Select and saving progress. In the main menu you now can access a Level Select screen. Everytime you reach a level your progress will be saved and you will be able to start from any level you reached.

- Pause Menu. I added a Pause Menu that can be opened by pressing "Backspace".

Thanks again to all of those who have been giving a chance to this game!