First attempt at ripping out agnostic code into ifcopenshell.api namespace. See #1399.

src/ifcopenshell-python/ifcopenshell/api/void/remove_opening.py

@@ -0,0 +1,20 @@
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {"opening": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        to_remove = [] # See bug #1224
+        for rel in self.file.by_type("IfcRelVoidsElement"):
+            if rel.RelatedOpeningElement == self.settings["opening"]:
+                to_remove.append(rel)
+                break
+        for rel in self.file.by_type("IfcRelFillsElement"):
+            if rel.RelatingOpeningElement == self.settings["opening"]:
+                to_remove.append(rel)
+                break
+        self.file.remove(self.settings["opening"])
+        for element in to_remove:
+            self.file.remove(element)