A more customizable and easy-to-replace navigator

[Tiagoperes]

The navigator is currently very complex and not customizable.

If the developer wants to develop a navigation logic or animation different than the one we implemented, it may be quite hard for him/her to do so.

1. How do we create an easy to use API for building custom navigators?
2. How do we make our navigator more customizable?

This issue should be updated with the answers to these questions and a plan to address the problem.