Rewrite in Swift
* Cleaner drawing code. Now things are broken up into several methods.
* All of the state that was computed each draw call is now cached in ivars for performance. This also cleans up some of the draw code.
* The `drawHand` method is now really nice thanks to Swift.
* Improve date kerning and positioning
* Command-W now works in the demo app
Rename ClockTest to ClockDemo