support for gen_config's info file

use special template mailman2sympa to set much more settings
also set 'info' based on 'advertised'
improved migration of subscribe_policy, added support for unsubscribe_policy
support for mapping private_roster to 'review'
support for anonymous_list, max_message_size and digestable
added comment about ignored/unsupported mailman settings
write list info into given info file

write out blacklist.txt and whitelist.txt for sympa
fix generated config for sympa-6.2.70

- converted from zsh to bash
- fixed path to helpers
- using REMOTE mailman via ssh
- new member importer using mailman-subscribers3.py to generate a
  dumpfile for restore_user, now supporting all kinds of digest,
  nomail, notmetoo and hide flag, mod flag also possible but not yet
  supported in sympa
- dropped notify_owner stuff

it's still very general, but previously it broke multiline html

previous privatekeyandeditorkeyonly discarded mails from persons not on
the list. This may be wrong depending on the use case. Now everything is
moderated.