uses currStage instead in TankAttack, removes arg
uses currStage instead in TankAttack, removes arg

ruslan120101/TankAttack-JavaFX,ruslan120101/JavaFX-TankAttack,ruslan120101/TankAttack-JavaFX,ruslan120101/TankAttack-JavaFX,ruslan120101/JavaFX-TankAttack,ruslan120101/JavaFX-TankAttack