New ConvertNestToAggregate patch recipe

src/ifcpatch/ifcpatch/recipes/ConvertNestToAggregate.py

@@ -0,0 +1,34 @@
+class Patcher:
+    def __init__(self, src, file, logger):
+        """Convert nesting relationships to aggregate relationships
+
+        Some software like Revit won't load nested children elements because
+        they (incorrectly) don't consider it to be part of the spatial tree.
+        For example, 12D software will use nesting.
+
+        This patch converts all nest relationships into aggregate
+        relationships.
+
+        See bug: https://github.com/Autodesk/revit-ifc/issues/706
+
+        Example:
+
+        .. code:: python
+
+            ifcpatch.execute({"input": model, "recipe": "ConvertNestToAggregate", "arguments": []})
+        """
+        self.src = src
+        self.file = file
+        self.logger = logger
+
+    def patch(self):
+        for rel in self.file.by_type("IfcRelNests"):
+            new = self.file.createIfcRelAggregates(
+                ifcopenshell.guid.new(),
+                rel.OwnerHistory,
+                rel.Name,
+                rel.Description,
+                rel.RelatingObject,
+                rel.RelatedObjects,
+            )
+            self.file.remove(rel)