Added System.Collections.IDictionary (non-generic) to ObservableDictionary
Added DictionaryTests.cs along with test methods for all relevant ObservableDictionary additions related to IDictionary implementation.
Updated UpdateCollectionHelper so that it implements System.Collections.ICollection along with ICollection.
Project file addition of DictionaryTests.cs.
Added System.Collections.IDictionary (non-generic) to ObservableDictionary Added DictionaryTests.cs along with test methods for all relevant ObservableDictionary additions related to IDictionary implementation. Updated UpdateCollectionHelper so that it implements System.Collections.ICollection along with ICollection.
Project file addition of DictionaryTests.cs.