Idea: Demo previewing

[TheLetterZed]

I saw that you were considering adding demo rendering in #56. I think it would also be cool to support demo previewing! I saw that https://dribble.tf/ has a lightweight demo renderer, and I think it would be useful to see the demo play out as a preview before deciding to render it. Would be neat to get this integrated into the project somehow. 😁

[rmburg]

Thanks for your suggestion, I'll look into it :)

Note that features like this won't make it into v1, and I want to get v2 into a more finished state before implementing something as complex as this. Nevertheless, this sounds very cool and I'd be happy to work on it some time in the future.