Overwrite parts if they already exist

This allows using the Boxes object multiple times with different settings

boxes.py

@@ -583,8 +583,8 @@ See --sy for format""")
         if name is None:
             name = part.__class__.__name__
             name = name[0].lower() + name[1:]
-        if not hasattr(self, name):
-            setattr(self, name, part)
+        #if not hasattr(self, name):
+        setattr(self, name, part)
         if isinstance(part, Edge):
             self.edges[part.char] = part