First-pass fixes for HXSL 2.0

This is definitely not working correctly, but at least it compiles!

Unfortunately I don't know enough about Stage3D to diagnose the issue(s)... as an example, if you create a new flambe project with the following class, the swf has a shaded green square at (0, 0) instead of the desired red square at (100, 100).

```haxe
import flambe.Entity;
import flambe.System;
import flambe.asset.AssetPack;
import flambe.asset.Manifest;
import flambe.display.FillSprite;

class TestMain
{
    private static function onSuccess (pack :AssetPack)
    {
    }

    private static function main ()
    {
        System.init();
        sprite.x._ = 100;
        sprite.y._ = 100;
        System.root.addChild(new Entity().add(sprite));
    }
}
```