Optimize for translation

Info for plugin author(s):

Plugin is not compatible with language packs: Missing load_plugin_textdomain().
https://developer.ww.wp.xz.cn/plugins/internationalization/how-to-internationalize-your-plugin/#loading-text-domain

Its been discussed several times on Polyglots team meeting, but its still up to author to do that properly, and Plugins team has point to do not make it a mandratory, because of flexibility (other ways can be used to localize plugin, or decide to not to localize it at all).