Force class on FlxTypedGroup.recycle()

I was having problems with FlxTypedGroup.recycle(). The object returned was a super class of the class passed to the function because ```Std.is(object, Class)``` will return ```true``` if ```object``` is ```Class``` or ```Class``` is a super class of the ```object``` class.
For example, before this commit:
```haxe
class Note extends FlxSprite { ... }
class LongNote extends Note { ... }

class PlayState extends FlxState {
	override public function create():Void {
		var group:FlxTypedGroup<FlxSprite> = new FlxTypedGroup<FlxSprite>();
		// Add a LongNote and Note objects
		group.add(new LongNote());
		group.add(new Note());
		
		for (n in group.members) {
			n.exists = false;		// Set exists to false so we can recycle them
		}
		
		var note:Note = cast(group.recycle(Note), Note);	// Should return a Note object
															// but, because the first object 
															// available is a LongNote and
															// its super class is Note, it
		trace(Type.getClassName(Type.getClass(note))); 		// will return that LongNote object
		
		var long:Note = cast(group.recycle(LongNote), LongNote);	// Should return a LongNote object
																	// but, because there are no more
																	// LongNote objects to return, it
		trace(Type.getClassName(Type.getClass(long)));		 		// will return a new LongNote object
		
		super.create();
	}
...
}
```
With this commit:
```haxe
class Note extends FlxSprite { ... }
class LongNote extends Note { ... }

class PlayState extends FlxState {
	override public function create():Void {
		var group:FlxTypedGroup<FlxSprite> = new FlxTypedGroup<FlxSprite>();
		// Add a LongNote and Note objects
		group.add(new LongNote());
		group.add(new Note());
		
		for (n in group.members) {
			n.exists = false;		// Set exists to false so we can recycle them
		}
		
		var note:Note = cast(group.recycle(Note, null, true), Note);
															// Should return a Note object.
															// The first object available is
															// a LongNote but we are forcing it
															// to be a Note object. It will return 
		trace(Type.getClassName(Type.getClass(note))); 		// the old Note object
		
		var long:Note = cast(group.recycle(LongNote, null, true), LongNote);	
															// Should return a LongNote object
															// Because the first object available
															// is a LongNote it will return 
		trace(Type.getClassName(Type.getClass(long)));		// will return that Longnote object
		
		super.create();
	}
...
}