Added static Starling.all property to get all Starling instances

[joshtynjala]

Similar to Starling.current, but it gets all Starling instances. An instance is added in its constructor and removed when its dispose() function is called.

Use Cases

1. I have a reference to a starling.display.Stage. It would be nice if I could somehow get the starling.core.Starling instance that owns it. For instance, I might want to know the nativeStage that is associated with this Starling stage so that I can position something properly above Starling in an AIR NativeWindow. Looping through the vector returned by the static Starling.all property would allow me to find the right Starling instance pretty easily.

2. An AIR NativeWindow has a stage property, which makes it easy to access the native display list of the active window with NativeApplication.activeWindow.stage. However, there's no way to get a Starling stage for an arbitrary NativeWindow. Similar to the previous use case, I can loop through the static Starling.all property and check if NativeApplication.activeWindow.stage matches a Starling instance's nativeStage property.

[PrimaryFeather]

I can see what you mean, Josh — yes, that makes sense! I merged that change into the master branch.

Thanks! 😄

[joshtynjala]

Thank you, Daniel!