user clicks with left mouse to add points,
		 right         delete.

points x,y coordinates are stored in array[100].
				...or linked list, i guess...


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FOR A GIVEN SET OF POINTS :

mean : x = sum up all x-coords, divide by total pts.
       y = 	  ... y-coords... 

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convex hull peeling:

-compute convex hull of all points (can take code from a CH website)
-mark all points on convex hull.
-if there exist any unmarked points, delete marked points and repeat.
-else take mean of marked points.
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simplical depth:

-