Support multiple player lives
Allow having more than one life for the player with the moddable default set to 3. In a slight change, when the player contacts an enemy, it loses a life in addition to being reset to the original position. Similarly, falling into a danger zone resets the position in addition to losing a life.
The lives are indicated by a row of hearts in the HUD. For simplicity, a TextureRect that tiles the heart on expansion is used. It would probably be more flexible to use a GridContainer.