should escape control characters

[hmh]

Although the code is capable of escaping a few control characters, it is not checking for them before it decides whether output should be escaped or not (Unicode codepoints 0000h to 001fh), so they make it to the output as-is (unquoted).

To test, add \u000a to the value of any of the unquoted fields in the example.

Fixing this would be extremely trivial and the slowdown should be negligible (unlike, say, really fixing it for all Unicode control characters).