Slightly increase spacing when arranging models

This is closer to the behaviour in Cura 4.7 and earlier. It makes it easier to pull objects apart, and to break them off from a raft.

cura/Arranging/Nest2DArrange.py

@@ -36,6 +36,7 @@ def findNodePlacement(nodes_to_arrange: List["SceneNode"], build_volume: "BuildV
         found_solution_for_all: Whether the algorithm found a place on the buildplate for all the objects
         node_items: A list of the nodes return by libnest2d, which contain the new positions on the buildplate
     """
+    spacing = int(1.5 * factor)  # 1.5mm spacing.
 
     machine_width = build_volume.getWidth()
     machine_depth = build_volume.getDepth()
@@ -99,7 +100,7 @@ def findNodePlacement(nodes_to_arrange: List["SceneNode"], build_volume: "BuildV
     config = NfpConfig()
     config.accuracy = 1.0
 
-    num_bins = nest(node_items, build_plate_bounding_box, 10000, config)
+    num_bins = nest(node_items, build_plate_bounding_box, spacing, config)
 
     # Strip the fixed items (previously placed) and the disallowed areas from the results again.
     node_items = list(filter(lambda item: not item.isFixed(), node_items))