Bouncing and Painting

New entity: The Rubber Cube (neutral) It spawns in caves. It looks a slime, but yellow and not transparent. When you attack it, it attacks you. If you kill it, it drops rubber. New item: Bouncy Ball (made with 1 slime ball in the middle and 8 rubber surrounding it). Item is the size of a slime ball, but yellow. When you throw it, it bounces around for several seconds before dropping, like a real world bouncy ball. New Enchantment: Bounce Break Use on a bouncy ball to make it strong enough to break blocks when thrown at them. Efficient tool for mining. New Enchantment: Speed Bounce Allows bouncy ball to drop faster when bounced. New Block: The Easel (crafted with 6 sticks) When you place it, it takes up the space of a door. Can hold the Canvas block. New block: The Canvas (crafted with 9 paper) Can be placed on the easel block or hanged on a wall. New item: Paint brush (crafted with 2 sticks & 1 feather) Use the paintbrush to doodle on the canvas. New item: The Marker (crafted from 2 sticks & 1 ink sac) When you hold it in your off hand, you can draw on paper, a bouncy ball, or a canvas.