Add an empty display changer script for Blender.

utilities/blender/change_every_empty_to_single_arrow.py

@@ -0,0 +1,6 @@
+import bpy
+for obj in bpy.data.objects:
+    if obj.type != 'EMPTY':
+        continue
+    obj.empty_display_type = 'SINGLE_ARROW'
+    obj.empty_display_size = .33