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

src/ifcopenshell-python/ifcopenshell/api/material/remove_material.py

@@ -0,0 +1,23 @@
+import ifcopenshell
+
+
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {"material": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        inverse_elements = self.file.get_inverse(self.settings["material"])
+        self.file.remove(self.settings["material"])
+        # TODO: this is probably not robust enough
+        for inverse in inverse_elements:
+            if inverse.is_a("IfcMaterialConstituent"):
+                self.file.remove(inverse)
+            elif inverse.is_a("IfcMaterialLayer"):
+                self.file.remove(inverse)
+            elif inverse.is_a("IfcMaterialProfile"):
+                self.file.remove(inverse)
+            elif inverse.is_a("IfcRelAssociatesMaterial"):
+                self.file.remove(inverse)