Move framerate calculation from step() to stepAndDraw()
Make the framerate property a constant
Create and use CHANNELS_PER_PIXEL constant
Move code to new generateStatePixelColour() method
Miscellaneous improvements to comments, quotes, layout
Change "FPS" constant to "targetFPS" property
Create new changeTargetFramerate() method
Create new setCellState() method
Move framerate-measuring functionality from GOL to GOLAnimator
Use Compass to compile CSS