snapshot after project re-org

cmd/tictactoe/main.go

game/game.go

game/game_test.go

go.mod

grid/cell.go

grid/cross/cross.go

grid/cross/cross_test.go

grid/empty/empty.go

grid/empty/empty_test.go

grid/grid.go

grid/grid_test.go

grid/nought/nought.go

grid/nought/nought_test.go

grid/position.go

player/player.go

players/bot/bot.go