Programming Assignment:  
 
                   Extending the Point class and
                  implementing a Comparator class
                        for sorting points.

                   Due:  Monday, June 18 @11:30am


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Part I:

   Complete and document the unimplemented methods after the TODO comment:

             radius()  // distance to origin
  
             angle()   // Theta according to Polar coordinates

             distanceTo(Point)  // Euclidean distance

             rotate(double)  // rotate counter-clockwise
                             // amount given in degrees

             readPoints(Scanner)

   Format assumed by readPoints:  just a sequence of double values
   where the first and second values are x1 and y1 and so on.

   Example:  2 7 3 9 2 -9
       represents points (2,7), (3.9), (2,-9)

   Error checking:  if you reach an input token that cannot
   be read as a Double, stop and return the collection of points
   you've read so far.  If the input doesn't specify the y-coord
   of the last point (i.e., the number of values is odd), simply
   ignore the last x-coordinate.

   Note:  Collection is an interface.  Many classes implement it
   including ArrayList.

Part II:

    Complete and document the PointCmp class which implements the 
    Comparator interface.  It should behave as described in the
    comments (allowing ordering by either x or y).

    Recall that the compare(a, b) method is suppose to return:

           a negative number if "p1 < p2"
           zero if p1 and p2 are equal
           a positive number if "p1 > p2"


References:

     Comparator interface:  

        http://docs.oracle.com/javase/7/docs/api/java/util/Comparator.html

     Scanner class:

        http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html

     Collection interface:

        http://docs.oracle.com/javase/7/docs/api/java/util/Collection.html

     Math class:

        http://docs.oracle.com/javase/7/docs/api/java/lang/Math.html

     Polar coordinates:

        http://en.wikipedia.org/wiki/Polar_coordinate_system