News reading app improvements

- SAXPArser no longer used; custom parser implemented
- News article list provides only article titles (no longer feed title)
- pim.NewsStoring.countNewArticleInGroup() added
- News group list shows number of unread articles
- app.news.NewsGroupWrapper class added for data associated with news groups
- NumberUtil class for Russian language added
- Delete key in groups list marks all articles as read; backspace does the action reversed to tab
- Minor language improvements