Do not copy presentation styles when copying a material

Ideally, presentation styles are reused. For example, 5 types of concrete can all use the same presentation

src/ifcopenshell-python/ifcopenshell/api/material/copy_material.py

@@ -29,6 +29,9 @@ def copy_material(file: ifcopenshell.file, material: ifcopenshell.entity_instanc
     If a material set is copied, the set items are also copied. However the
     underlying materials (and profiles) used within the set items are reused.
 
+    If a material is associated with a presentation style, that presentation
+    style is reused.
+
     :param material: The IfcMaterialDefinition to copy
     :type material: ifcopenshell.entity_instance
     :return: The new copy of the material
@@ -92,7 +95,7 @@ def _copy_material_with_inverses(file, material):
 
         elif inverse.is_a("IfcMaterialDefinitionRepresentation"):
             inverse = ifcopenshell.util.element.copy_deep(
-                file, inverse, exclude=["IfcRepresentationContext", "IfcMaterial"]
+                file, inverse, exclude=["IfcRepresentationContext", "IfcMaterial", "IfcPresentationStyle"]
             )
             inverse.RepresentedMaterial = new
     return new

src/ifcopenshell-python/test/api/material/test_copy_material.py

@@ -67,6 +67,7 @@ class TestCopyMaterial(test.bootstrap.IFC4):
         ifcopenshell.api.run("style.assign_material_style", self.file, material=material, style=style, context=context)
         new = ifcopenshell.api.run("material.copy_material", self.file, material=material)
         assert new.Name == "CON01"
+        assert len(self.file.by_type("IfcPresentationStyle")) == 1
         assert len(self.file.by_type("IfcMaterialDefinitionRepresentation")) == 2
         assert new.HasRepresentation[0] != material.HasRepresentation[0]
         assert new.HasRepresentation[0].Representations[0] != material.HasRepresentation[0].Representations[0]