Hearts and snowballs

Collectible hearts were added to give player credit for staying on the path. To make the game a little but more exciting snowballs are rolling down the hills.

Tech note: There is no simple way of checking for collisions in Three JS or Ammo JS but there is a built in function for checking distances between vectors (mathematically more correctly it's points) so that is what I used for the collission detection between the ball and the hearts.