Usage
```js
Navigation.setDefaultOptions({
      topBar: {
        backgroundColor: 'red'
      }
    });
```

* disabled back gesture support

* changed disabledBackGesture prop name to popGesture

* upgraded detox to version 6.x.x

* fixed detox script, added release config

* readme

* fix

* Reorder dependencies

Keep vs code happy

* Make markdown files readable on MacDown

* BackHandler compatibility

Give precedence to react's BackHandler when hardware back button is pressed

* f

* Update test

* Restore deps

This reverts commit 076ee7311e.

* readme

* dewfault values

setTabButton -> has now the property 'label' to change the label of the TabButton

iOS update style-update rutine to update each viewcontroller in a NavigationViewController
tabButtonColor improvement

This reverts commit 4a12632364.

* Add converter for UIBarButtonSystemItem

* Add support for UIBarButtonSystemItem-styled buttons

* Add documentation about systemItem

* V2 overlay skeleton (#2097)

* skeleton

* basic test

* remove useless files

* remove useles files

* semicolon

* refactoring

* rm useless files

* alert dialog more styles

* hot fix

* tests

* e2e with own alert

* fix test

* fix ios e2e

* custom dialog WIP

* WIP

* refactor custom dialog

* fix e2e

* gitignore

* fix js tests

* remove hardcode

* snackbar

* drop FAB for now

* fix test

* readme

* WIP

* ios, tests

* refactoring

* current tab

* android tests

* readme

* current tab index ios

* fix tests

* readme

* test fix

* probabl test fix

* push/pop promise

* tests

* modal

* other

* fix tests

* probably test fix

* readme

* WIP

* ios, tests

* refactoring

* test fix

* probabl test fix

* setTabButton -> has now the property 'label' to change the label of the TabButton

* Add to documentation

* [BugFix] use i instead of 0 to check all TabItems

Add the preview and pop feature

To use the feature you simply call `navigator.push()` but with additional parameter `previewViewID` which is a React Node.

```js
<TouchableOpacity
  onPressIn={() => this.props.navigator.push({
    screen: 'screenid',
    previewView: this.viewRef,
    previewActions: [{
      title: 'Foo',
      style: 'selected', // none, selected, destructive
      actions: [{ title: 'Bar' }],
    }],
 })
/>
```

This commit saves navBar component props in propsRegistry and restores the saved props
when the component is mounted, allowing us to pass unserializable props to custom navBar component.