* Letting a NaturalPlayer select the promotion piece with a combo box
* Optimized reflection use in PawnPromotion
* Changed toString method of Move to use LAN
Closes#9
* Moved move execution and reversion to the Move class
* Removed Move.Type enumeration
* Added Move subclasses Castling, EnPassant and PawnPromotion
* Generating all four possible pawn promotions in the Pawn class
* Temporarily removed special move support from NaturalPlayer