Subshaping for nested compounds in STEP export

I suggest changing the XCAFCoc_ShapeTool::CheckSubShape method to allow subshaping of nested compounds:

static Standard_Boolean CheckSubShape (const TopoDS_Shape &S, const TopoDS_Shape &sub)
{
if ( S.IsSame ( sub ) ) return Standard_True;

if ( !(S.ShapeType() == TopAbs_COMPOUND
&& sub.ShapeType() == TopAbs_COMPOUND) ) //KA
if ( S.ShapeType() >= sub.ShapeType() ) return Standard_False;

for ( TopoDS_Iterator it(S); it.More(); it.Next() ) {
if ( CheckSubShape ( it.Value(), sub ) ) return Standard_True;
}
return Standard_False;
}