While namespaces act for hierarchy, modules are something like "tags" -
usable when you want to check related classes of e.g. CubeMapTexture.
Not sure how to name module for Math and Physics namespaces and
Contexts/Trade, though.
Long-standing TODO. It is better to have size first, because it is more
significant than type (e.g. because there are Vector4<T> specializations
and not VectorT<4> specializations). It is also IMHO easier for user to
distinguish/read the type than before:
Vector<float, 4> -> Vector4<float> // before
Vector<4, float> -> Vector4<float> // now