This library primarily performs the boolean clipping operations -
intersection, union, difference & xor - on 2D polygons. It also performs
polygon offsetting. The library handles complex (self-intersecting) polygons,
polygons with holes and polygons with overlapping co-linear edges.
Input polygons for clipping can use EvenOdd, NonZero, Positive and Negative
filling modes. The clipping code is based on the Vatti clipping algorithm,
and outperforms other clipping libraries.