INT E0 - PCROBOTS v1.41 - "GET_SHELL_STATUS" - FIND OUT WHAT HAPPENED TO SHELL

	AX = 0023h
Return: BX = status of last shell to land
	    0000h missed completely
	    0001h hit a wall
	    0002h hit a robot within 50-square radius
	    0003h hit a robot within 25-square radius
	    0004h hit a robot within 5-square radius