A first-principles implementation of arithemetic in Python

I was thinking about the nature of numbers after reading this[1]. It occured to me that you could implement them in software. I couldn't get the idea out of my head so to calm myself down I just decided to get it done.

It lacks elegance in certain places (it uses loops, there is definitely a nicer way out there of defining zero-ness, and the Number.one etc variables are a bit ugly), so feel free to fork it and beautify it (or add features).

[1] http://betterexplained.com/articles/a-visual-intuitive-guide...