This is a breaking change and has to be opt-in. To prevent host.clear from being called,
Override `clearHostOnActivityDestroy` in MainApplication and return false:

```java
    @Override
    public boolean clearHostOnActivityDestroy() {
        return false;
    }
```

If host isn't cleared, the next time the app is opened react context might still be initialized.
In this case we emit appLaunched event which has to be handled in Js:

```js
  Promise.resolve(Navigation.isAppLaunched())
      .then((appLaunched) => {
        if (appLaunched) {
          startApp();
        }
        new NativeEventsReceiver().appLaunched(() => {
          startApp();
        });
      })
```

This converts from using a deprecated attribute.

* add disabledButtonColor in order to set navigation button disabled color

* add disabledButtonColor to the docs

Fixes #1007

* Add font family support on bottom tabs

* import missing classes

* import missing class

* update document

* Support customize icon for left nav button in android

* Add navBar navBarTextFontSize support for android

* Add missing parameter instruction for in app notification

* Merge changes as origin master

Ability to set a flat border under the TopBar. `topBarElevationShadowEnabled` should be set to true if using this feature.

* testing

* test

* try fix props on topTabs

* Test xml menu

* Add titleBarHeight

* Remove test

* Add to StyleParams

* Add topTabsHeight

* Fix styleParams type

* Add navBarFontBold

* Add typeface package

* Remove unused debugging

* add adjust soft input optional config for Lightbox on android platform

* Add doc about adjustSoftInput for showLightBox

* Add initialTabIndex support to RCCTabBarController

* Add initialTabIndex support to BottomTabsLayout

closes #1694

fixes #1675

To match the rest of the styling

As the screen api document mentions that it can be done statically, it's best to mention it here as well.

* Revert "Add custom bar button item class (#1641)"

This reverts commit 80ae102456.

* Revert "Export `Navigator` class for public use (#1647)"

This reverts commit 1770113321.

* Revert "Hide back button when calling resetTo (#1469)"

This reverts commit 518e372e05.

* Revert "Add isRootLaunched implementation on Android"

This reverts commit 6f4aca32a6.

* Revert "Fixed LightBox not updating overlay width/height on rotate (#1461)"

This reverts commit 54d2531720.

This allows for custom React Native views to be rendered as a bar button item in the navigation bar.

* Make Navigator Public

* Make Screen.js export both Screen and Navigator

* Update Navigation.js to import Screen correctly

* Make Navigator public for Android too

* Forgot to export after importing

* ESLint fix

* ESLint fix

* ESLint Fix

* ESLint Fix

returns true if NavigationActivity is resumed (startApp was called)

* Fixed LightBox not updating overlay width/height on rotate

* Cleaned up bounds

* Removed unneeded call