* Add screen visibility listener which can be registered globally

API
new ScreenVisibilityListener({
    willAppear: ({screen, timestamp}) => console.log(`Displaying screen ${screen}`),
    didAppear: ({screen, timestamp}) => console.log(`Screen ${screen} displayed in ${Date.now() - timestamp} millis`)
  }).register();

todo
* Add timestamp to modal, resetTo
* implement unregister
* implement iOS

* Add global screen visibility listener to example app

* Think I better assign a value to emitter

* Send timestamp in resetTo

* Moved listener to library, it can be deleted from the app

* Add push and resetTo buttons to pushed screens

* Send appear/disappear events after animation ends

* Pass pop timestamp from js

* Send timestamp in popToRoot

* Add popToRoot button in push screen

* Add few navigation buttons to modal screen

* Pass timestamp to tabs

relevant only to first/initial tab

* Update timestamp when navigating between BottomTabs

* Send screen visible events after modal dismiss

* log willDisappear and didDisappear

* Report both start and end timestamps

* Implement unregister

* Send NavigationType parameter in visibilityEvent

This indicates the type of the navigation command that triggered the visibility change

* Rename pushInitialScreen to more explicit name

* Fix duplicate initialScreen visibility events

* Update screen visibility log statement

* Show popToRoot in modal screen only if screens were pushed

* implement global screen event for iOS

* fix lint issues

Orientation was reverted to the app orientation each time modal was dismissed.

Change bottom tab bar button image at runtime

Usage is identical to switchToTab, closes #842

* React Native v0.40.0 fixes

* Implement disableIconTint property on Android TitleBarButtons

* Show contextual menu only on Modal, if showing

* Fix crash if font not set in title bar button parameters

This is mostly a workaround to overcome faults in the simple event bus implementation,
also fixes crash when reloading while modal is displayed.

Support status bar color in Modals

fixes #1034

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

Closes #681

closes #661

* [android] Basic implementation of orientation change event and getter

#dasdsa

* [android] Check if fabAnimator is not null

* [android] Add configChanges prop to NavigationActivity in AndroidManifest

* [android] Fix duplicate declaration of onConfigurationChange

* [android] Use EventEmitter class to dispatch orientation change events

* 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.

* WIP

* Core function works e2e

* Queued overlays support

* Remove unneeded activity ref

* Add post-PR changes

call setButtons with empty fab object to remove it

* Implement right SideMenu on Android

* Adapt toggleSideMenu and toggleSideMenuVisible to right SideMenu

* NavigationActivity implements PermissionAwareActivity

* NavigationActivity implements PermissionAwareActivity

* Fixed code styling

* Removed Hungarian notation.

* Removed empty line

fixes #493

closes #464

Notify the Activity layout that the top most Modal was dismissed only
if no other modals are displayed. Currently this event is used as a
`onVisible` event to to the layout. This whole logic can be simplified
when we implement proper screen visibility events.

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.

This reverts commit d3582d2780.

This commit adds support for displaying an activity with no animation
by setting `animationType: none` when calling `startApp`. In the future
we can support more animation types if there's a demand for it.