053 - Playdate 3D #3

Part 3 of building a 3D renderer from scratch for the Playdate in Swift. Today the points finally rotate: we write a rotation function from the classic 2D rotation formula, build a proper Point3D struct, add translateZ(by:), and fight with delta time until the animation runs at a sane speed. Next up: faces, so it looks like an actual cube, and hooking rotation up to the crank.