Add cleanup function

bc.lua

@@ -138,6 +138,8 @@ function bc:init(my_address, local_nouns, local_verbs)
   end
   -- Change this for deployment VVV
   o.modem = modem:init(my_address, modem_listener)
+  -- Save listener function for deinit
+  o.modem_cb = modem_listener
   -- Init local stuff
   o.local_verbs = local_verbs or {}
   o.local_nouns = local_nouns or {}
@@ -268,4 +270,9 @@ function bc:listen_cancel(n, id)
   end
 end
 
+-- Deinit
+function bc:cleanup()
+  event.ignore("modem_message", self.modem_cb)
+end
+
 return bc