F# QuickStart example

Hello,

I have translated the QuickStart/Game.cs sample into F#. It works well (tried on Windows, Linux and Mac), and I thought you'd like to add it in the Examples directory. I think it would be cool to have at least one sample for each supported language.

Here is the file: http://laurent.le-brun.eu/fsharp/opengl.fs.

Btw, I really enjoyed OpenTK. It's a great project!

Laurent.