Fix of https://github.com/prusa3d/Slic3r/issues/214

Dent in perimeters around a hole

Clipper Offset has been extended to remove tiny edges before the offset.
This is important as the tiny edges pose difficulty
for normal calculation, leading to various adverse effects like
kinks and dents in the offsetted contour.

xs/src/libslic3r/Point.hpp

@@ -38,6 +38,7 @@ class Point
         return Point(scale_(x), scale_(y));
     };
     bool operator==(const Point& rhs) const { return this->x == rhs.x && this->y == rhs.y; }
+    bool operator!=(const Point& rhs) const { return ! (*this == rhs); }
     std::string wkt() const;
     std::string dump_perl() const;
     void scale(double factor);