ENH: improve auto arranging and by-object printing

1. In auto arranging bed temp can be higher than vitrify temp by no more than 15 degrees.
2. In by-object printing we use max radius for clearance
3. Add P1P max radius

Change-Id: If595f3e19fd74f6f36d2f394edbb835c413cc800
(cherry picked from commit 2af42420ad3770f0728adb583082600544519a58)

src/libslic3r/Arrange.cpp

@@ -78,6 +78,7 @@ using ItemGroup = std::vector<std::reference_wrapper<Item>>;
 
 // A coefficient used in separating bigger items and smaller items.
 const double BIG_ITEM_TRESHOLD = 0.02;
+#define VITRIFY_TEMP_DIFF_THRSH 15  // bed temp can be higher than vitrify temp, but not higher than this thresh
 
 // Fill in the placer algorithm configuration with values carefully chosen for
 // Slic3r.
@@ -423,9 +424,9 @@ protected:
             for (int i = 0; i < m_items.size(); i++) {
                 Item& p = m_items[i];
                 if (p.is_virt_object) continue;
-                score += lambda3 * (item.bed_temp - p.vitrify_temp > 0);
+                score += lambda3 * (item.bed_temp - p.vitrify_temp > VITRIFY_TEMP_DIFF_THRSH);
             }
-            score += lambda3 * (item.bed_temp - item.vitrify_temp > 0);
+            score += lambda3 * (item.bed_temp - item.vitrify_temp > VITRIFY_TEMP_DIFF_THRSH);
             score += lambda4 * hasRowHeightConflict + lambda4 * hasLidHeightConflict;
         }
         else {

src/libslic3r/Print.cpp

@@ -448,7 +448,7 @@ StringObjectException Print::sequential_print_clearance_valid(const Print &print
                 convex_hull = offset(convex_hull_no_offset,
                         // Shrink the extruder_clearance_radius a tiny bit, so that if the object arrangement algorithm placed the objects
                         // exactly by satisfying the extruder_clearance_radius, this test will not trigger collision.
-                        float(scale_(0.5 * print.config().extruder_clearance_radius.value - EPSILON)),
+                        float(scale_(0.5 * print.config().extruder_clearance_max_radius.value - EPSILON)),
                         jtRound, scale_(0.1)).front();
                 // instance.shift is a position of a centered object, while model object may not be centered.
                 // Convert the shift from the PrintObject's coordinates into ModelObject's coordinates by removing the centering offset.

src/slic3r/GUI/Jobs/ArrangeJob.cpp

@@ -388,7 +388,7 @@ void ArrangeJob::prepare()
 
         params.clearance_height_to_rod             = print.config().extruder_clearance_height_to_rod.value;
         params.clearance_height_to_lid             = print.config().extruder_clearance_height_to_lid.value;
-        params.cleareance_radius                   = print.config().extruder_clearance_radius.value;
+        params.cleareance_radius                   = print.config().extruder_clearance_max_radius.value;
         params.printable_height                    = print.config().printable_height.value;
         params.allow_rotations                     = settings.enable_rotation;
         params.allow_multi_materials_on_same_plate = settings.allow_multi_materials_on_same_plate;