More modernization

- Split generic "common" libraries into specific libraries
- Use other packages in lieu of custom code
- General cleanup

Application/Options/BulkFeedWindow.xaml.cs

@@ -1,5 +1,4 @@
-using Common.Wpf;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
 using System.Windows;
@@ -36,7 +35,7 @@ namespace FeedCenter.Options
             ShowDialog();
         }
 
-        void HandleCollectionViewSourceFilter(object sender, FilterEventArgs e)
+        private void HandleCollectionViewSourceFilter(object sender, FilterEventArgs e)
         {
             var checkedListBoxItem = (CheckedListItem<Feed>) e.Item;