This PR adds support for setting stack root with multiple children, which is to be expected as stack can be initialised with multiple children.
Closes #4441

* Handle pop and dismissModal rejections - #3914

* Added e2e

* Update TextScreen.js

mergeOptions support for commands

This reverts commit e1ee3d5f99.

This reverts commit 2d879ccd0c.

* Constants support

* Change Navigation.constants() to an async function on Android

Also added topBarHeight and bottomTabsHeight

* Assign commandId to async commands

* CommandListener refactor

Pull listener out of Navigator and implement NativeCommandListener for native commands

* Emit onNavigationEvent when commands complete

* Rename timestamp to completionTime

* Rename NavigationEvent to EventEmitter

* Rename sendOnNavigationButtonPressed to emitOnNavigationButtonPressed

* Emit navigationEvent on bottom tab select

* rebase fix

* Emit commandCompleted event instead of nativeEvent

* fix native ios commands

* wait show and dismiss Overlay

* migrate js and java to mergeOptions

* migrate ios to mergeOptions

* overlay support

* default options support
* refactored navigation options

* async commands for all events

* test fix

* async await for push and showModal

* async await for push and showModal

* refactored custom transitions

* refactored custom animations

* screen Background Color iOS

* ios v2 topBarTextFontFamily

* added topBarHidden to iOS

* minor fix and topBarHideOnScroll

* minor fix

* topBarButtonColor iOS

* topBarTranslucent iOS

* topBarTranslucent IOS minor fixes

* eslint fixes

* minor fixes

* changed setTabBadge to tabBadge and added a unit test in iOS

* added fontSize on iOS

* minor fix

* topBarTransparent

* minor fix

* first dirty custom transition iOS poc. in need of complete refactor and testing

* dirty poc for view transition

* dirty poc of interactive transition

* deleted unNeeded Files

* cleaning

* cleaning, support for interactiveImagePop and backButton custom transition

* cleaning

* merge v2 into custom-transition-animation fix

* merge fix

* merge fix

* cleaning and merge fix

* support for multiple animation in parralel, animations with are not shared element including: velocity, spring, alpha and translate

* last commit should also include these

* added resize mode animation and fixed flickering bug

* refactoring

* first cleaning and another test

* cleaning

* commandsHandler now accepts bridge in constructor, fixed tests, added e2e test

* eslint

* android pop now recieves two parameters - preparation for custom transition

* Refactor + add afterLoad to modal

* merge v2 second try

* merge fix

* merge fix

* fix ios unit tests

* fixed topBarTransparent e2e

* fix js tests

* refactored RNNAnimator, RNNAnimatedView, small fixes

* refactor topBarLargeTitle

* fixed lifycycle bug with componentWillUnmount, small fixes

* fix transparent conflict

* removered Element.js from coverage report

* comment redundent test
(still needs to be discussed), small fix

* removed commented test, moved element.js to adapters

* readme

* WIP

* ios, tests

* refactoring

* current tab

* android tests

* readme

* current tab index ios

* fix tests

* readme

* test fix

* probabl test fix

* #1071 Test that Navigator forwards NavigationOptions to ViewController

* Add an argument allowing to run a single Android e2e test

* Fix style issue

* #1071 Allow changing navigation title in iOS

* Update readme to document an option for running a single test

* Update ScreenStyleDynamic.test.js