Apple2Mac first cut and refactor common rendering code

    * Based on NSOpenGLView and Apple's GLEssentials sample code
    * CVDisplayLink- or NSTimer-driven rendering
    * Works in window or fullscreen mode on Mac OSX Lion or later

TODO FIXME:
    * Breaks Linux/Posix build
    * Cocoa menu interfaces
    * Key/mouse/joystick/gamepad handling