Updater overwrites configurations

[pionsys-mhs]

I know the update functionality is still an experimental feature, but here are some topics i have come across when updating my servers that would be really nice if the update process would consider:

1. /srv/modoboa/instance/instance/settings.py
   I do have a few custom configurations in this file like USE_X_FORWARDED_HOST = True, modifications to ALLOWED_HOSTS, EMAIL_CLIENT_CONNECTION_SETTINGS, MODOBOA_APPS, MIDDLEWARE and AUTHENTICATION_BACKENDS for e.g. LDAP. The modifications are lost on update and needs to be added again

2. /etc/dovecot/conf.d/10-auth.conf
   The activation of LDAP with !include auth-ldap.conf.ext gets deactivated on update

3. /etc/postfix/master.cf
   I use SMTPS for my servers and on every update SMTPS gets deactivated again. SMTPS could/should also be the default rather than SMTP + STARTTLS

4. /etc/rspamd/local.d/dkim_signing.conf
   My custom fix for Modoboa 2.6.5 - Rspamd DKIM problem #617 gets overwritten on every update.

5. /etc/apt/sources.list.d/rspamd.list
   The 2 lines for the rspamd repo are added/appended on every update, leading to warning on the next sudo apt update

Other than these topics, the update process works great - thank you.