Game menu/UI

[philsupertramp]

We need some kind of nice looking interface. I'll provide a mockup later. These things need to be implemented

• start screen
  • load game from file
    • regular old .txt file containing turns in already implemented notation
  • create game
    • color selection
    • turn time limits selector
• game end screen
  • allow saving game, use TurnHistory.save(...) for this
  • allow replaying turn history