Fixed TOC space width

Fix TOC space width in order to support multibyte character.

![before](https://cloud.githubusercontent.com/assets/186170/5589038/ece9deb6-9158-11e4-84e6-65591ec65938.png)
![after](https://cloud.githubusercontent.com/assets/186170/5589039/ed030260-9158-11e4-9546-19c6929134aa.png)