Feature work schedule (#1419)

* ifcopenshell.api modules Persons and Organisations account for IFC4 SCHEMA CHANGE

* New Feature to manpiulate Work Plans

src/ifcopenshell-python/ifcopenshell/api/sequence/remove_work_schedule.py

@@ -0,0 +1,14 @@
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"work_schedule": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        # TODO: do a deep purge
+        if self.settings["work_schedule"].HasContext:
+            rel_declares = self.settings["work_schedule"].HasContext[0]
+            if len(rel_declares.RelatedDefinitions) == 1:
+                self.file.remove(rel_declares)
+        self.file.remove(self.settings["work_schedule"])