Ported Slic3r::BridgeDetector to XS

xs/src/libslic3r/Polyline.cpp

@@ -1,4 +1,5 @@
 #include "Polyline.hpp"
+#include "Line.hpp"
 #include "Polygon.hpp"
 
 namespace Slic3r {
@@ -10,6 +11,12 @@ Polyline::operator Polylines() const
     return polylines;
 }
 
+Polyline::operator Line() const
+{
+    if (this->points.size() > 2) CONFESS("Can't convert polyline with more than two points to a line");
+    return Line(this->points.front(), this->points.back());
+}
+
 Point
 Polyline::last_point() const
 {