OnPropertyChanged is now virtual so it can be overriden if needed

Author: ShawnLaMountain

src/ThunderDesign.Net-PCL.Threading/Collections/ObservableCollectionThreadSafe.cs

@@ -164,7 +164,7 @@ public void Move(int oldIndex, int newIndex)
             OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removedItem, index));
         }
 
-        public void OnPropertyChanged(string propertyName)
+        public virtual void OnPropertyChanged(string propertyName)
         {
             this.NotifyPropertyChanged(PropertyChanged, propertyName, WaitOnNotifyPropertyChanged);
         }

src/ThunderDesign.Net-PCL.Threading/Collections/ObservableDictionaryThreadSafe.cs

@@ -133,7 +133,7 @@ public bool WaitOnNotifyCollectionChanged
             return result;
         }
 
-        public void OnPropertyChanged(string propertyName)
+        public virtual void OnPropertyChanged(string propertyName)
         {
             this.NotifyPropertyChanged(PropertyChanged, propertyName, WaitOnNotifyPropertyChanged);
         }