Duplicate
Fixes #1234: use dash instead of underscore to separate language and country in locale id.
Changed usage of self to static to allow extendibility

code style section has been added here:
https://github.com/yiisoft/yii2/wiki/Core-framework-code-style#self-vs-static

verification code for properties:
https://gist.github.com/cebe/7566916
Merge remote-tracking branch 'yii/master'
Pretty url