All scalars are treated as strings

[neckberg]

Currently, all scalar values are interpreted as strings, even if, for example, they are purely numeric.

I think a good solution would be the following:
By default, if a scalar is numeric, or equal to 'true', 'false', or 'null', we set it to true, false, ornull, not just a string. And if someone wants their value to be treated as a string, they should put it in a literal, like so:

```
false
```

And when converting to markdown, we should automatically add the back ticks if it is a string.

Note that this would be a breaking change.