Rest of the path chaining has been replaced with the new algorithm.

PolylineCollection.cpp/hpp was removed, use Polylines instead.
Various first_point() / last_point() now return references, not copies.

src/libslic3r/SupportMaterial.cpp

@@ -923,7 +923,7 @@ namespace SupportMaterialInternal {
         //FIXME add supports at regular intervals to support long bridges!
         bridges = diff(bridges,
                 // Offset unsupported edges into polygons.
-                offset(layerm->unsupported_bridge_edges.polylines, scale_(SUPPORT_MATERIAL_MARGIN), SUPPORT_SURFACES_OFFSET_PARAMETERS));
+                offset(layerm->unsupported_bridge_edges, scale_(SUPPORT_MATERIAL_MARGIN), SUPPORT_SURFACES_OFFSET_PARAMETERS));
         // Remove bridged areas from the supported areas.
         contact_polygons = diff(contact_polygons, bridges, true);
     }