Complete the rib wipe tower port in WipeTower2

The rib tower is now always square (prime_tower_width is ignored, as the
GUI already implies), carries the rib origin offset like the BBL tower so
the rib tips sit inside the configured position, clamps the rib length to
the tower diagonal, and extends the ribs for short towers.

src/libslic3r/GCode/PrintExtents.cpp

@@ -143,7 +143,8 @@ BoundingBoxf get_wipe_tower_extrusions_extents(const Print &print, const coordf_
     double wipe_tower_y = print.config().wipe_tower_y.get_at(plate_idx) + plate_origin(1);
     Transform2d trafo =
         Eigen::Translation2d(wipe_tower_x, wipe_tower_y) *
-        Eigen::Rotation2Dd(Geometry::deg2rad(print.config().wipe_tower_rotation_angle.value));
+        Eigen::Rotation2Dd(Geometry::deg2rad(print.config().wipe_tower_rotation_angle.value)) *
+        Eigen::Translation2d(print.wipe_tower_data().rib_offset.cast<double>()); // tower-local rib-wall shift, zero unless rib
 
     BoundingBoxf bbox;
     for (const std::vector<WipeTower::ToolChangeResult> &tool_changes : print.wipe_tower_data().tool_changes) {