Fix minor error and update MANIFEST

lib/Slic3r/Layer/Region.pm

@@ -249,7 +249,7 @@ sub make_perimeters {
                     # $loop is the outermost loop of an island
                     my @holes = ();
                     for (my $i = 0; $i <= $#$holes_pt; $i++) {
-                        if ($loop->contains_point($holes_pt->[$i]{outer}->first_point)) {
+                        if ($loop->polygon->contains_point($holes_pt->[$i]{outer}->first_point)) {
                             push @holes, splice @$holes_pt, $i, 1;  # remove from candidates to reduce complexity
                             $i--;
                         }

xs/MANIFEST

@@ -1648,7 +1648,6 @@ src/boost/utility/swap.hpp
 src/boost/utility/value_init.hpp
 src/boost/version.hpp
 src/boost/visit_each.hpp
-src/voronoi_visual_utils.hpp
 src/BoundingBox.cpp
 src/BoundingBox.hpp
 src/clipper.cpp