Fixed missing window title on startup with no files on commandline
Warning and message when loading or saving read-only files
Save empty text keys in the primary culture; save cultures sorted

The translation file is unchanged, just saved in the new order of culture names.
Fixed loading/culture bug; comment/suggestions toolbar icon

* Fixed loading bug for adverse culture order and primary culture
* Replaced comment and suggestions toolbar icons
* Colour indicator for comment and suggestions in the toolbar, if data is available
* Lighter and italic dummy suggestion text
* Improved loading performance of suggestions a bit