Creates a vertex specification. The program is used to find the attribute location.
Unuse this vertex specification. If you are using a VAO, you don't need to call it, since the attributes would be tied to the VAO activation.
Use this vertex specification.
Returns the size of the Vertex; this size can be computer after you added all your attributes
A VertexSpecification's role is to describe a Vertex structure. You must instantiate it with a compile-time struct describing your vertex format.