Added Fluent Navigation

[grahammendick]

Solves the problem of constructing links with pre-populated crumb trails. For example, how do you build a link to 'person' with the 'people' crumb populated so that back navigation works?

var stateNavigator = new StateNavigator([
  {key: 'people', route: ''}
  {key: 'person', trackCrumbTrail: true}
]);

If the user navigates from 'people' to 'person' then the crumb is populated. Fluent navigation solves the problem of manually constructing this same link. Can't just call getNavigationLink('person', {id: 10}) because that only works if the current state is 'person'. Don't want to have to navigate to 'person' state first because that changes the UI.

Fluent navigation allows navigation without changing the current state or UI. Can then access the url from the fluent context.

var link = stateNavigator.fluent()
  .navigate('people')
  .navigate('person', {id: 10})
  .url;

// link: /person?id=10&crumb=%2F
stateNavigator.navigateLink(link);

Especially useful for Navigation React Native (not released yet) where need to pre-populate the crumb trail stack when coming to the app from a notification, for example.