Separate interface for dealing with FEN, basic fen validation
Added index methods to Square
Exmerimental UI display prototype
Support en passant square in Position
Added Game interface + initial implementation
Implement equals & hashCode for Move
Game navigation responsibility moved to GameNavigator
Test navigation to initial position
Implement FenParser.parse(String)
Navigation from initial to initial shouldn't do anything
Use Game interface in SimpleTextUi & add Back button
Implement Position.diffTo(Position)