Update state syncer (class DatabaseWidgetStateSync) to account for new
features:
- properly sync view state when switching tabs
- properly read/write view state from/to config
Update classes EntryModel and EntryView to consistenly name list/search
modes. Before, both classes defined list mode as 'group mode' and search
mode as 'entry list mode', which differed from naming in other classes
such as DatabaseWidget.
