Removed unnecessary imports and debug output via <iostream>.
Class game updated with functions to check on a winner. One not implemented completely nor tested, yet.
Checking on winner is completely implemented now but delivers false results.
Improved functions for checking on a winner. Checking vertically apparently works but is not fully tested, yet.
Adapted scene to work properly with game (_currentPositionStone is now only being reset to 0 if a stone could successfully placed.). Tracing a stone vertically and checking if there is a winner vertically now works properly though tests are still missing.
Tracing for winner horizontically apparently works now...
Checking on a winner is now fully implemented but not tested completely, yet.
Hotfix for segfault if game is not started with default values for rows (6) and columns (7): Default-values of constructor are now 9 for either rows and columns to prevent segfault when creating an instance via assignmentoperator with a desired size other than the default values of 6 & 7 (segfault appeared because the field of the old instance was copied into the new instance which caused a segfault because the old instance had a smaller field than the new one.).
Merged with branch xperimental.