Change bottom tab bar button image at runtime

Usage is identical to switchToTab, closes #842

* Global bottomTabSelected event

* ios - add bottomTabSelected and bottomTabDeselected events

* Added an additional navigation event for the press of an already selected tab

* Renamed new navigation event to bottomTabReselected

Since fab set dynamically wasn’t saved in screen params, when returning
to that screen the fab wasn't displayed.

This commit also enables setting fab dynamically in modals

* Add .hideInAppNotification on android.

- Separate hide and show animations.
- Implement a little bit of throttling around successive calls to .showInAppNotification

* Update example to demo dismiss.

* Don’t create SideMenu button automatically on Android

* Remove left button and add it dynamically

* Fix resetTo animation on Android

Up until now resetTo would destroy the current stack and create a new
one. This was an easy implementation but resulted in jurky
(none existent) animations.
This commit changes resetTo behavior. Instead of recreating the stack,
the we reset to is pushed to the stack, and the other elements are
removed when show animation ends.

* Fix bug in popToRoot when keyboard is visible

* Add comments

* code review changes

* Add final to function parameters

* WIP

* Core function works e2e

* Queued overlays support

* Remove unneeded activity ref

* Add post-PR changes

This commit also introduces a tempprary fix to an issue where fab is
displayed on wrong screen when switching between bottom tabs rapidly.

* Dispatch a navigation event whenever the side menu button is clicked (BottomTabsLayout)

* Dispatch a navigation event whenever the side menu button is clicked (SingleScreenLayout)

* Changed the way the navigatorEventId is retrieved in SingleScreenLayout.

The event is sent to the top most screen displayed in the current screenStack.

call setButtons with empty fab object to remove it

* Implement right SideMenu on Android

* Adapt toggleSideMenu and toggleSideMenuVisible to right SideMenu

* Move event emmiter logic out of Application

* Implement searchView

Usage:
```js
rightButtons: [
      {
        id: 'searchView',
        label: 'Search',
        hint: 'Search...'
      }
    ]
```

* Translucent TitleBar

* Collapse TopBar

* Less noticeable translucent effect

* Implement ScrollViewDetector

* Collapse on fling

* Collapse on touch up

Complete collapse on touch up instead of fling

This change means that in a tab based app, when pushing a screen
which did not declare `tabBarBackgroundColor` - the BottomTabs color
will persist from the previous screen and not be set to the default
color which is white. This eliminates the unwanted BottomTabs
background color change in this specific use case.

closes #409

When ivoking navigation actions such as push, pop etc, instead of
checking modal visibility, check if modal actually contains the given
navigator. This fix alows to change navigation state in screens while
modal is displayed.

* Don't show fab of a screen that's pushed to a none active tab
* Change fab when navigating back in the stack with back button
* Add screens before SnackbarAndFabContainer

fixes #274

* Created Snakbar class to encapsulate Snackbar logic.
* Clicking the action now emits event to current screen
* Action color works