Fills were reimplemented in C++.

While reimplementing the FillPlanePath code, the octagon infill was fixed to extrude the right amount of material.

xs/src/libslic3r/Fill/FillConcentric.hpp

@@ -0,0 +1,20 @@
+#ifndef slic3r_FillConcentric_hpp_
+#define slic3r_FillConcentric_hpp_
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class FillConcentric : public Fill
+{
+public:
+    virtual ~FillConcentric() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+	virtual bool no_sort() const { return true; }
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_FillConcentric_hpp_