ScoreIndicator fix, code tidy

Airport, GameWindow, TransferBar:
-removed unused import

ScoreIndicator:
-fixed needle offset
-clarified constructor parameter
scene stack corrections; GameEnd fixed

Main:
-fixed setScene()
+no longer closes the scene when it may yet be returned to

DifficultySelect, FindGame, LobbyConfig:
-closes itself so it may not be returned to

GameOver:
-no longer has to assume DifficultySelect instance exists to close

GameEnd:
-no longer tries to guess the scene stack; just closes itself
-correctly updated the textbox so that text draws
multiplayer game over state handled

tcpConnection:
-host now ensures the client accepted is the one requested
-host now closes the server socket when no longer needed
-now handles closure gracefully !?

Multiplayer:
-positioning for scoreIndicator updated
-correctly identifies left/right player for scoreIndicator
-now correctly switches scenes on game over
-removed console spam
-disabled returning to the previous scene using Escape key