Improve Kotlin support

[pedrovgs]

We are going to update all the project documentation and add a new module supporting Kotlin properly. We will make the library more idiomatic and kotlin friendly so our Android users can enjoy it 😃

[pablichjenkov]

If you plan to refactor I would suggest not using the Renderer.clone() technique when creating new Renderer instances. I suggest to delegate the Renderers creation to the outter layer. Like passing a Factory of Renderers to the RendererBuilder. Cloning is not very explicit and may create confusion some times.