Website redesign

Hey everybody,
I finally found some time to redesign the AsciiMath website! =)
I tried to stick to a very clean and open github like design style. I also added most of the syntax and included some special cases I wish I had known when starting out with AsciiMath.

So what you do think? Shall we merge it, are there any typos or mistakes? Any additions?

Best regards!
easy-to-write