The plural/paucal form support was not compatible with pylupdate4, it
didn't correctly parse the 3-argument calls to translate.
This fixes it, and updates the sources accordingly.
Unfortunately, I didn't manage to automatically provide all the languages that are available as *.qm files. By now we have to manually set the combobox items and the list for the languages in the bitmessageqt/__init__.py
Cleanup of the translation files. All the *.pro files are now similar and the *.ts files are updated and ready for further translation. Newly released the *.qm files.
There's still an error when trying to change back from "ru" or "ru_RU" to any other language. However, this doesn't happen in other languages.
This is set to work with the gracefull degrade (e.g. 'de_CH' to 'de' if there is no such file).
There's no warning about the need to restart. I think it is obvious, so i don't think we need it, but i can add it if you want.
