Negative sign in `AQF` mode is indistinguishable from `,`

```js
const x = { text: '-1' };
const xStringified = JsonURL.stringify(x, { AQF: true });
const parsed = JsonURL.parse(xStringified, { AQF: true });
console.assert(parsed['text'] == x['text'], 'parsed should be equal to x');
```

`"-1"` gets encoded as `(!-1)`  and it gets parsed as `",1"`.