mwolson: Initial migration of exim4 settings to deleuze

mwolson: Initial migration of exim4 settings to deleuze

* exim4/update-exim4.conf.conf: Set up.  Configure dc_visiblename here,
  which is used to set qualify_domain later on.

[other files are relative to exim4/conf.d/]

* acl/30_exim4-config_check_rcpt: Add recommended lines from
  /usr/share/doc/mailman/README.EXIM.gz so that bounce messages get
  through, even if they are from a malformed address

* acl/40_exim4-config_check_data: Use built-in spam checker rather than
  running email through spamc.  This should make the configuration much
  simpler.

* auth/30_exim4-config_examples: Migrate userdb_plain.  Disable plain.

* main/01_exim4-config_listmacrosdefs: Don't define domains here -- we
  will do that in a separate file to make things easier for domtool.  Add
  tls_cipher to MAIN_LOG_SELECTOR as per old config.  Use
  file_transport=address_file for /etc/aliases delivery, as per old
  configuration

* main/10_domtool-domains: New file where the domain list will be written
  to by domtool.

* main/20_mailman-macros: Migrate mailman configuration settings here.
  Use the longer option names for clarity.

* router/310_exim4-config_virtual_user: New file that routes mail for
  hosted domains.  From old config.

* router/320_exim4-config_mailman: New file that routes mail for mailing
  lists.  From old config.

* router/450_exim4-config_default_aliases: New file containing
  default_aliases rule for various domains; mostly seems to be used by
  Adam.  From old config.

* transport/10_exim4-config_mailman: New file containing the transport
  for mailman lists.  From old config.  Use the aforementioned longer
  option names.

* transport/40_exim4-config_virtual_delivery: New file containing
  transport used to deliver mail to virtual mailboxes.  From old config.
  Should we be using a postgresql/mysql database here?  It's what most
  other sites seem to do, according to Google.