Add option for automatic backfilling when creating portal

mautrix_telegram/config.py

@@ -1,5 +1,5 @@
 # mautrix-telegram - A Matrix-Telegram puppeting bridge
-# Copyright (C) 2019 Tulir Asokan
+# Copyright (C) 2020 Tulir Asokan
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License as published by
@@ -113,6 +113,11 @@ class Config(BaseBridgeConfig):
         copy("bridge.delivery_receipts")
         copy("bridge.delivery_error_reports")
         copy("bridge.resend_bridge_info")
+        copy("bridge.backfill.invite_own_puppet")
+        copy("bridge.backfill.takeout_limit")
+        copy("bridge.backfill.initial_limit")
+        copy("bridge.backfill.missed_limit")
+        copy("bridge.backfill.disable_notifications")
 
         copy("bridge.initial_power_level_overrides.group")
         copy("bridge.initial_power_level_overrides.user")