Any Japanese users? Rated 4 out of 5 stars

Maybe it doesn't work for Japanese users these days.
It causes by breaking Japanese language file, so I fix it.

Here is Japanese compatible version.
http://knoa.jp/up/imagetweak.0.23.ja.xpi

Detail of this problem is here:
https://github.com/CAFxX/ImageTweak/issues/18

This review is for a previous version of the add-on (0.23.1-signed.1-signed).