Yaml, more features

This PR adds support for more yaml types. To make the tests pass, it needs the fixed version of timestamp>rfc3339 from 622f333, but as discussed in https://github.com/slavapestov/factor/pull/1057 622f333 is just a proof of concept and is not meant to be merged in.

I can also modify the failing test to not use decimals and remove 622f333 if that's better ?
Rather, this still passes the tests:

```factor
: write-rfc3339-seconds ( timestamp -- )
    second>> dup ratio? [
        1 mod >float number>string rest write
    ] [ drop ] if ;
```