Deletes Acount points starting at position Index.
xyzArray a = new xyzArray(4); a[0]= new xyz(1, 1, 1); a[1]= new xyz(1,-1, 2); a[2]= new xyz(3, 4, 2); a[3]= new xyz(2, 2, 1); a.delete(1, 2); //now a has count = 2; // a[0] = (1, 1, 1); // a[1] = (2, 2, 1); //