Reworked algorithm for Voronoi Offset curve extraction.

Now the algorithm is very different from the OpenVoronoi implementation
and hopefully it is now correct (save numerical issues, which will be
a big PITA).

src/libslic3r/CMakeLists.txt

@@ -190,6 +190,7 @@ add_library(libslic3r STATIC
     MTUtils.hpp
     VoronoiOffset.cpp
     VoronoiOffset.hpp
+    VoronoiVisualUtils.hpp
     Zipper.hpp
     Zipper.cpp
     MinAreaBoundingBox.hpp