Write a program that repeatedly reads the x-y coordinates of points in
the Cartesian plane and prints a message telling either an axis on
which the point lies or the quadrant in which it is found. As soon as
an user enters 0 twice meaning that x=0 and y=0, the program stops.
Sample lines of output:
	(-1.0, -2.5) is in quadrant 3
	(0.0, 4.8) is on the y axis
Hint: When x > 0, y > 0, the point is located in the 1st quadrant. 
      When x < 0, y > 0, the point is located in the 2nd quadrant.
      When x < 0, y < 0, the point is located in the 3rd quadrant.
      When x > 0, y < 0, the point is located in the 4th quadrant.

Ref: Hanly, Ch. 4, p.217, P6.