Expose A Portable Web Runtime?
Recently I wrote [wasm4-playground](https://grantshandy.github.io/wasm4-playground) which uses a slightly modified version of the main web runtime. The site had to be built with this repository as a git submodule so it can create its own "frontend" to the runtime by directly importing source from the git submodule. This works *fine*, but it's not very good practice and it's not very easy to do for one-off creations.

Right now I'm writing a blog post that uses WASM-4 and I had the idea of putting interactive versions of the game inline with the document. I think this could become a pretty common use of WASM-4, and implementing it wouldn't be that hard.

Here's an idea I have for what an API might look like:
```javascript
let game = new Wasm4Game({
    width: number,
    height: number,
    elem: HtmlElement,
    cartUrl: string,
    cartBase64: string,
    cartBytes: Uint8Array,
    captureFocus: boolean,
    enableReset: boolean,
    silenceLogging: boolean,
});

game.start();
game.stop();
game.reset();

game.loadCartUrl(string);
game.loadCartBase64(string);
game.loadCartBytes(Uint8Array);
```

Adding this would enable someone to make a page on wasm4.org which allows you to just upload your own `.wasm` file and play it right there on the site without it being on its own page in the "Play" section. This would also enable a lot more experimentation with embedding WASM-4 in websites.

When it's done it could be hosted as a minified JS lib on wasm4.org or more likely published as an NPM package so people can use one of the many CDNs that mirror it.

Does this sound like something that belongs here? If there's enough demand I can write it myself and create a PR.