After Integer>>asFloat, Fraction>>asFloat needs a review too.
It is not broken. But it has unreachable code, performs more
arithmetic than necessary and we could put some light on obscure
comments and reduce implicit knowledge.
So if we can leave a better example of coding in the image, let's do it.
It's better to write this in a Blog
http://smallissimo.blogspot.com/2011/09/reviewing-fraction-asfloat.html
because it would be too long for a single commit comment.

Nicolas