[ALOY-815] iOS 7: add 'navigationWindow' API to XML markup

Feature description

With the new iOS 7 the new "navigationWindow" API has been introduced for handling the navigation logic for iOS 7. Using a classic Titanium project, the sample code would be:

var rootWin = Ti.UI.createWindow({
	backgroundColor:"white"
});

var navWin = Ti.UI.iOS.createNavigationWindow({
	window:rootWin
});

var secondWin = Ti.UI.createWindow({
	backgroundColor:"blue"
});

var b1 = Ti.UI.createButton({
	title:"PUSH"
});
rootWin.add(b1);

var b2 = Ti.UI.createButton({
	title:"POP"
});


secondWin.add(b2);

b1.addEventListener('click',function(){
	navWin.push(secondWin)
});

b2.addEventListener('click',function(){
	navWin.pop(secondWin)
});

navWin.open();

Details

navigationWindow is supposed to be the top-level container (is a Window proxy, not a View). Is going to work as alternative Ti.UI.iPhone.NavigationGroup (which is going to be deprecated) Should also work if used in Ti.UI.iPad.SplitWindow.

Notes

I think the expected behavior is to be able to use it pretty much in this way:

<Alloy>
	<NavigationWindow id='navigation'>
		<Window id='mainWin'>
			<other stuff...>
		</Window>
	</NavigationWindow>
</Alloy>

Then I guess that windows could be added or removed from the navigationWindow using something like:

var newWin = Alloy.createController('newWin').getView();
$.navigation.push(newWin);

and

$.navigation.pop(newWin);

Additional info

Attached you can find also an Alloy sample code using the navigationWindow element defined in the index controller instead of in the .xml markup