Compatibility with react-pixi.

[whisper2shade]

Hi,

I've been struggling with including scrollbox into my react-pixi project for quite some time and i finally figured out that the PixiComponent wrapper automatically adds the children into Scrollbox, but in the wrong container. I made this small change to expose the viewport's addChild methods, so that react-pixi would add the children in the proper place.

I think it's safe to do, because the internals of scollbox should not be modified outside anyway and when modifying the code, you can always call super.addChild(...) to add children to scrollbox itself.

[whisper2shade]

Just a note, i'm not a react or javascript expert, so please check if there are no problems that i might have missed. :)

[davidfig]

Hmm...this may cause problems since you won't be able to add children outside of content. I'm sure there are some people that hack the scrollbox in this way (I may be one of those people). What might be better is to write pixi-scrollbox as a react component and handle this case directly in the component.