Retina support

Hi,

i've created a version with OSX 10.8 style and retina support.
Subpixel antialiasing is only applied to text, ASCII-art elements are not antialiased for reduction of subpixel artifacts on HiDPI resolution.

![preview](https://f.cloud.github.com/assets/5290789/1145387/048956c8-1e0f-11e3-97bb-fe91a84ccf5f.png)