#3818659 i18n: Language empathy mode

This is a first sample implementation of what we’re calling Language Empathy mode. It allows a user to experience Calypso in a translation state of language X:

• All text that is actually translated will appear in English.
• All text that is not translated, will print “I don’t understand”.

Here is an example screenshot for Croatian:

You could enable it like this:

Todo:

• Add Empathy checkbox to language selector
• Make it more obvious that you are in empathy mode.
• Find a better way than just displaying “untranslated”, for example rather add styling?

see also D44550-code and Automattic/i18n-issues#27