Unexpected escaping

[tcoughlin3]

Hi @hanford thanks for your work on this library. I was testing it out and I think I came across a bug. Not 100% sure what's going on but I think with the recursion the concatenated output string is hitting the default switch case and callling escapeHtml(children) 2 more times than needed.

When calling serialize({"children":[{"type":"p","children":[{"text":"& , \" < >"}]}]})...

Expected output: '& " < >'

Actual output: '& , " < >'

[hanford]

@tcoughlin3 hmmm probably because of 497431b

I'd accept a PR that includes a fix (and a test!) if it's problematic for you

[dylans]

I'm not convinced this should be calling escaping html at all because it's supposed to be serializing ast to markdown, not html. Shouldn't it instead leave < > and & alone, and turn ' and " into ' and " instead?