code: public boolean equals2D(final Coordinate c, final double tolerance) {
          if (!equalsWithTolerance(this.getX(), c.getX(), tolerance)) {
              return false;
          }
          if (!equalsWithTolerance(this.getY(), c.getY(), tolerance)) {
              return false;
          }
          return true;
      }
docs: Tests if another coordinate has the same values for the X and Y ordinates. The Z ordinate is
  ignored.
  
  @param c
  a <code>Coordinate</code> with which to do the 2D comparison.
  @param tolerance
  margin of error
  @return true if <code>other</code> is a <code>Coordinate</code> with the same values for X
  and Y.