4x3 Support

This adds 4x3 support in addition to 16x9 support. This is mainly to support CRT screens to help make Kart a good solution for an arcade cabinet frontend.

You can pick the aspect ratio you you want to use in the settings.

![screen shot 2014-05-29 at 1 35 26 am](https://cloud.githubusercontent.com/assets/260/3114432/305d7740-e6f3-11e3-9bf0-2d52d6ffb966.png)