Fine-tuning gravity

Before we test out our new flying code, we need to make one adjustment. The default gravity setting of 9.8 feels too real. Pierre lives in a cartoon world; real-world gravity is a bit of a drag. We can adjust gravity in the GameScene class; add this line at the bottom of the didMove function:

// Set gravity 
self.physicsWorld.gravity = CGVector(dx: 0, dy: -5)