Correctly justify Unicode characters in terminal

Many Unicode characters take more spaces than one ASCII character. For
example, Chinese characters are two characters wide when using monospace
font in terminal. This patch use wcwidth of Markus Kuhn to count the
correct width for justification.
Use mk_wcwidth instead mk_wcwidth_cjk
Merge pull request #243 from kanru/justify-cjk

Correctly justify Unicode characters in terminal