FlxG.cameras: fix reset() not removing all cameras

[Leonix]

The problem is that FlxG.cameras.reset() tries to remove elements of an Array while iterating over it.
This fails to .destroy() half of all cameras, leading to the memory leak.

---

• Flixel version: 4.2.0
• OpenFL version: 3.6.1
• Lime version: 2.9.1
• Affected targets: at least Neko, likely more
• Observed behavior: Process memory usage steadily goes up.
• Expected behavior: It should not.

---

Code snippet reproducing the issue:

package;
import flixel.FlxG;
import flixel.FlxState;
import flixel.FlxCamera;

class PlayState extends FlxState
{
	override public function create():Void
	{
		FlxG.cameras.add(new FlxCamera());
	}

	override public function update(elapsed: Float):Void
	{
		super.update(elapsed);
		FlxG.switchState(new PlayState());
	}
}

[Gama11]

Looks like this is a regression from edf93b5.

Thanks!

[Leonix]

Note that unit test for this should probably test for whether FlxG.cameras.cameraRemoved signal is called for all cameras. Or whether all cameras were properly camera.remove()d. Checking only for list.length would pass on vanilla 4.2.0, too.

[Gama11]

You're right, I made a mistake when checking whether the test actually fails before your changes...