New system module with UI to browse systems in an IFC.

src/ifcopenshell-python/ifcopenshell/api/system/data.py

@@ -0,0 +1,24 @@
+class Data:
+    is_loaded = False
+    products = {}
+    systems = {}
+
+    @classmethod
+    def purge(cls):
+        cls.is_loaded = False
+        cls.products = {}
+        cls.systems = {}
+
+    @classmethod
+    def load(cls, file):
+        cls.products = {}
+        cls.systems = {}
+        for system in file.by_type("IfcSystem", include_subtypes=False):
+            if system.IsGroupedBy:
+                for rel in system.IsGroupedBy:
+                    for product in rel.RelatedObjects:
+                        cls.products.setdefault(product.id(), []).append(system.id())
+            data = system.get_info()
+            del data["OwnerHistory"]
+            cls.systems[system.id()] = data
+        cls.is_loaded=True