parse quoted strings containing newline and comma

[marvv]

I encounter the problem you mentioned in the TODO of thr project's document. When the header contains comma the lib can't parse the header correctly.

Also i've seen a pull request which try to fix this problem, i wonder if you have time to review the code.

I like the interface the lib offers after searching for a while， but do feel a little bit regret that the latest version is years ago.