Hi.

>Umm, there is still problem, but I think empty seq/map problem was solved by my patch.
>If there is no objection, I want to commit it tommorow or later.

I have commited but

---
[]: ""

seems to be allowed by yaml specification. (http://yaml.org/spec/current.html#simple%20key/)

Probably this is parser's bug not emitter's bug. Should I revert my change?
But above format cannot be parsed in 1.8.2. Hmm...