Investigate: Architecture upgraade

[OliverBenz]

GameSession = Data (Position) + GameHandler
GameHandler = variant <LocalGame, LanGame, FreePlay, etc.>

GameHandler(Position& pos); // constructor

The GameWidget has a Position& to get data and a GameHandler& to update data.
The GameHandler updates Position and emits signals.

Investigate also: Emit signals in Position or in GameHandler? It's logic so it should be in GameHandler but its data update so should be in data? Every data update requires signalling so keeping those together makes sense.