WIP: Add replace action to navigation and make navigation type more generic

[fakenickels]

Making navigation type more generic

navigation is now derived from the parametric type commonNavigation('a) so we can sure for instance the same header component across different StackNavigators.

let make = (~navigation: Rebolt.StackNavigator.commonNavigation('a), _children) => {
 ...component,
 render: _self => {
  <View>
   <BackButton onPress={(_) => navigation.pop()}>
 </View>
 }
}

navigation.replace(Config.route)

I moved around a couple of things to accommodate the replace action. Mainly they were

• Move the transition side effect logic from didUpdate to inside the reducer so the side effect is more explicit/direct
• Use Belt.Array to remove a screen by in RemoveStaleScreen (ReArray.remove, because of spliceInPlace, does not work with 0 indexes).

Missing

Add to the documentation

Let me know if I can improve anything else before merging