i18n: Use speaklater library to introduce lazy translation
Use lazy translation for loading messages
Move quotes to loading screen and make them lazy strings
Use lazy translation for status icon helptext
remove unnecessary import
Merge pull request #2077 from unknown-horizons/lazy-translation

Implements lazy translation that can be used to mark strings translateable outside of functions, i.e. during import time. This does *not* mean that we don't have to update all pychan widgets when the language changes.