Allow support for clearance geometry

src/ifcblenderexport/export.py

@@ -1115,7 +1115,7 @@ class IfcExportSettings:
     def __init__(self):
         self.has_representations = True
         self.has_quantities = True
-        self.subcontexts = ['Body', 'Axis']
+        self.subcontexts = ['Body', 'Axis', 'Clearance']
 
 print('# Starting export')
 start = time.time()