SLA archive import with miniz, marching square bugfixes

Fix compilation on Windows


Fix array subscript out of range error in MarchingSquares


Fix normals of mesh constructed from slices


Improve performance of mesh construction from slices

src/libslic3r/Zipper.hpp

@@ -28,7 +28,7 @@ public:
 
     // Will blow up in a runtime exception if the file cannot be created.
     explicit Zipper(const std::string& zipfname,
-                    e_compression level = NO_COMPRESSION);
+                    e_compression level = FAST_COMPRESSION);
     ~Zipper();
 
     // No copies allwed, this is a file resource...