FIX: rewrite per-object printing order logic

1. Previous logic can't guarantee left-to-right printing order, so
   toolhead may crash on the right side. In the new algorithm printing
   order is guaranteed.
2. Clearance radius should be the max of 3 directions (left, bottom,
   up), not including right, otherwise collision may happen on bottom or
   up directions.
3. Add is_extrusion_cali_object property to handle extrusion brim
   overlap better.

Change-Id: I44868b9925d983f5cca0c31d35dfa28d895fadbf

src/libslic3r/Arrange.hpp

@@ -52,6 +52,7 @@ struct ArrangePolygon {
     //BBS: add locked_plate to indicate whether it is in the locked plate
     int       locked_plate{ -1 };
     bool      is_virt_object{ false };
+    bool      is_extrusion_cali_object{ false };
     bool      is_wipe_tower{false};
     //BBS: add row/col for sudoku-style layout
     int       row{0};