Small vector and matrix proposed for phobos2 now on github

[#ponce]

I'm not sure how your static foreach is actually static. 

I think static foreach is a very good idea to minimize speed difference between debug and release versions (i know one shouldn't ship debug version, but sometimes you have to)...

> //Single element access does not require opDispatch
> writeln(v.x);
> 
> //Swizzling supported via opDispatch
> writeln(v.yzx); //2 3 1
> writeln(v.xxyyzx); //1 1 2 2 3 1


Can we get assignment through swizzle ? Like:
v.xy = vector2f(1.f, 2.f);

(but one should disallow: 
v.xx = vector2f(1.f, 2.f); )

Also, I like the naming, even though I would probably alias it anyway.

Existing solutions: vector3f, vec3f, smallVector3f, float3...