[Bf-committers] Normalise patch

[Michael Reimpell]

> It was setting
> super-small vectors to <0,0,0>, which really isn't a good behavior for
> something that's supposed to return vectors of length 1.

The normalise function is _not_ supposed to return a vector of unit length for 
the zero element of the vector space! Mapping 0 to 0 is the most reasonable 
mapping. Translation, e.g., 0 -> (0,0,1), has nothing to do with 
normalisation! Of course this applies to all floating point representations 
of the zero element, i.e., all vectors of length below a certain threshold.

Regards,
Michael