test: Fixed test to work with non default constructor.

And there's the reason why not to forbid the parameterless default constructor.
The user can easily instantiate the same with his own instantiation of CE3D::Vector.
Also I think when the user hasn't given a specific vector, the Paint() function shall fail when using non-initialized transformations inside the camera. This indicates the user to set some appropriate vectors.

So the question: Should I support again the parameterless default constructor?