jwg12 Unique IfcPolygonalFaceset Faces

[aothms]

Make IfcPolygonalFaceset.Faces a unique list, as discussed. Ordering is required for colours. Set is semantically more fit. So unique list good compromise.

[aothms]

--- tmp/a/IFC.exp	2022-08-26 21:40:44.648047300 +0200
+++ tmp/b/IFC.exp	2022-09-05 20:17:14.469379100 +0200
@@ -8616,21 +8616,21 @@
 	BoundaryType : SIZEOF(TYPEOF(PolygonalBoundary) * [
     'IFC4X3_DEV.IfcPolyline',
     'IFC4X3_DEV.IfcCompositeCurve',
     'IFC4X3_DEV.IfcIndexedPolyCurve'
   ]) = 1;
 END_ENTITY;
 
 ENTITY IfcPolygonalFaceSet
  SUBTYPE OF (IfcTessellatedFaceSet);
 	Closed : OPTIONAL IfcBoolean;
-	Faces : LIST [1:?] OF IfcIndexedPolygonalFace;
+	Faces : LIST [1:?] OF UNIQUE IfcIndexedPolygonalFace;
 	PnIndex : OPTIONAL LIST [1:?] OF IfcPositiveInteger;
 END_ENTITY;
 
 ENTITY IfcPolyline
  SUBTYPE OF (IfcBoundedCurve);
 	Points : LIST [2:?] OF IfcCartesianPoint;
  WHERE
 	SameDim : SIZEOF(QUERY(Temp <* Points | Temp.Dim <> Points[1].Dim)) = 0;
 END_ENTITY;