title: Error setting scrollFactor on FlxSprite after update to HaxeFlixel 3.3.0
body: <p>I just finished updating my HaxeFlixel install to 3.3.0 and after ironing out all the other upgrade changes I am still getting one error I can't find any explanation for. I am setting the <code>scrollFactor</code> property on the <code>FlxSprite</code>s that make up my background elements, and had no problem with it before 3.3.0. I can't seem to find any references to that property changing with the update.</p>
  
  <p>Here is the relevant code where I am setting the property:</p>
  
  <pre><code>//Setup bg
  var bg:FlxSprite;
  var scrollFactor:FlxPoint;
  for (i in 0...loader.bgArray.length){
      bg = new FlxSprite(0, 0, loader.bgArray[i][0]);
      scrollFactor = new FlxPoint(
          Std.parseFloat(loader.bgArray[i][1]),
          Std.parseFloat(loader.bgArray[i][2]));
      bg.scrollFactor = scrollFactor;
      add(bg);
  }
  </code></pre>
  
  <p>Here is my output from haxelib list:</p>
  
  <blockquote>
    <p>flixel: [3.3.0]<br> hxcpp: [3.1.30]<br> lime-tools: [1.4.0]<br> lime:
    [0.9.7]<br> openfl-html5: [1.4.0-beta]<br> openfl-native: [1.4.0]<br>
    openfl-samples: [1.3.0]<br> openfl: [1.4.0]<br></p>
  </blockquote>
  
  <p>When I run lime test flash in my project folder with the above snippet I get:</p>
  
  <blockquote>
    <p>source/PlayState.hx:54: characters 3-33 : Cannot access field or
    identifier scrollFactor for writing</p>
  </blockquote>
  
  <p>Line 54 is the one where I am setting <code>bg.scrollFactor</code>.</p>