Translator: major changes and additions. Moved Close Project menu item to Project menu. Added Save, Save All, Close and Close All menu items. Added class Document which all forms inherit from. Documents can indicated that they have been modified, they can be saved and closed. They are displayed as pages in the main tab widget. Fix: signals from changing the text in text controls programatically are ignored now. Fix: text taken from text controls must be passed to unicode() Catching errors from yaml.load() in classes LangFile and Project.