Added *.user to .gitignore
Implemented the by-key indexer in ObservableDictionary
Moved ObservableCollection and GridCoordinate classes to new namespace PathFind.Core
Use IDictionary where possible in ObservableCollection unit tests; Added unit test for GridCoordinate.GetHashCode
Added IObservableDictionary interface
Replaced Map.Dimensions property with RowCount and ColumnCount properties to eliminate dependence on System.Windows class in the model layer and to use integers rather than the doubles used by the Size struct
Added some unit tests to MapTests
Implemented ObservableDictionary.GetNumerator (the generic one)
Added dependency properties RowCount, ColumnCount to MapView. Bound to the corresponding model properties.