Snapshot 13: Adding goomba update function
Snapshot 14: Adding goomba handleMovementTrace method
Snapshot 15: Adding goomba and player collision properties
Snapshot 16: Adding collideWith method for goomba, player can be killed
Snapshot 17: Drawing player health in main.js
Snapshot 18: Giving player ability to kill goomba by jumping on it
Snapshot 19: Adding mushroom entity and basic animation
Snapshot 20: Adding update method for mushroom, it now moves
Snapshot 21: Mushroom now bounces off walls
Snapshot 22: Mushroom heals player on collision