KReversiView now controls game-flow, as it was done by KReversiScene

What's new:
1) KReversiView now have same signal pattern as KReversiScene, used
before. Now game is playable. You can do only allowed moves and so on.
2) Showing of legal moves and last move already works.
3) You can change chip color.
Known issues:
1) History works, but Undo doesn't.
2) Game sometimes crashes, when you close it while demomode is running.
3) QML layout don't fit board image well, so you can see that last cells
have some bias.