Release Name: 0.20

Notes:



Changes:
* Adapt to Ruby 1.9.x series.

* Change encoding rule at parsing to html document.
  For details, see the Encoding Rule. <http://ruby.morphball.net/bluefeather/doc/en/encoding-rule.html>

* Extend TOC format for specifing header-level.
  You can write TOC as {toc:h3-h4} or {toc:h3}.