Suggestion: Using strings instead of an enum for layer group in scratch-renderer

[Tacodiva]

In my opinion, it's kind of strange that these typing as they are right now only allow you to use the layer groups that scratch uses. As the comment in the enum says:

  const enum LayerGroup {
    // The renderer can be configured to use any strings as group names, but these are the groups
    // that scratch-vm uses, listed in order.
    Background = 'background',
    Video = 'video',
    Pen = 'pen',
    Sprite = 'sprite'
  }

What you name your layer groups is really a decision made by consumers of the scratch-renderer library and shouldn't be arbitrarily enforced by these typings. Because of this odd restriction, things like the playground example which come directly from scratch-render repo will not compile without casting or changing the layer group name to one of the four prescribed by the enum above.

I think this should be changed, but I though I'd create an issue because it seems to be a very deliberate decision and I was curious to hear your thoughts.

[GarboMuffin]

I think it would make sense to change it to'background' | 'video' | 'pen' | 'sprite' | string

[Tacodiva]

That sounds like a good compromise. Should I add it to the PR?

[GarboMuffin]

Sure