New Linking

Introduced a new workflow. The old workflow only used RBStoryboardLink. It was responsible for all the work by acting as a proxy for the real view controller. In the new workflow, RBStoryboardLink merely provides information for RBStoryboardSegue. RBStoryboardSegue redirects the segue on presentation. This redirection avoids the complexity of UIViewController containment and dereferencing a proxy in methods such as -prepareForSegue:sender:. The new workflow is thanks to @MBulli.