Add font size to ArticleList. Get rid of SearchListWindow.
Use prefs for font size in SingleItemWindow.
Use ContentProvider for the PDF history.
Use the ContentProvider to fill the widget.
Use the ContentProvider for RSSListWindow as well.

Remove the now unneeded arXivDB.
Add a font size setting to the preferences.
Make sure CategoriesListFragment notices prefs changes.
Remove fonts assets. Not used anymore.