- Renamed parameter "merge_feature" to "personalization_feature"

Limit personalization: Only when posted from WWSympa, entire text will be converted. Otherwise only footer/header will be converted.

MySQL: With MySQL 5.6, 5.7.6 and later sql_mode system variable contains STRICT_TRANS_TABLES by which some obsoleted columns such as date_admin causes "(42000) Invalid default value" error.  Fixed by resetting sql_mode to be empty, the default on 5.5.x or earlier.

Currently, if you want to report archived mail(s) as spam while asking for
deletion, the confirmation page is shown twice (only once if not reporting as
spam). It appears like a bug to users. This commit remove the
confirmation when reporting as spam (there is still the confirmation for
the deletion).

As of Postfix 2.3, Content of Return-Path: pseudo-header field added by pipe(8) for null envelope sender became "MAILER-DAEMON".  Empty `null_sender` option will prevent this behavior.
As a workaround, the uppercase "<MAILER-DAEMON>" will be treated as null envelope sender.

This allows you to invoke the command from "sendmail_aliases" without using the wrapper (#946).

Fix get_inactive_lists: the page was not listing the current list owners/editors because they were loaded the wrong way ->{'admin'}{'owner'} instead of ->get_current_admins.

<sympa-request> address should not be forwarded to any functions of Sympa.  To avoid mail loop by such misconfiguration, discard messages bound for this address.

There is no save method in Sympa::List anymore.

Relative to #993: with this option, we can rebuild all archives with a
simple `for` bash loop, without restarting from beginning if
`archived.pl` restarts while rebuilding all lists.

* review: Won't process sync_include in advance so that processing will be faster.

* Refactoring. Sympa::List::on_the_fly_sync_include() was removed. Instead, "include" request handler had "delay" option.

* Remove unused "last_sync" cache entries.  "last_change" entries remain.

* sync_include will no longer be invoked during Sympa::List->new():
  - No owner defined in a list is no longer treated as error_config.
  - Instead, if no owner defined,
     - If possible, discard incoming message and send back DSN to original sender,
     - or, notifications to owners will be redirected to listmaster(s).

* Refactoring: Remove unused functions

* Small refactoring: mail_tt2/listeditor_notification.tt2 is no longer used.

* Clarify log messages and DSN about undefined owner/editor/listmaster

* Merge @Sympa::ConfDef::params into %Sympa::ListDef::pinfo
* Merge %Conf::old_params into %Sympa::ListDef::pinfo
* Add aliases of parameter names for compatibility to sympa.conf/robot.conf of earlier versions.
* Move content of Sympa::ListDef to Sympa::Config::Schema
* Move content of Sympa::ConfDef to Sympa::Config::Schema
* Defining additional format entries in config schema.
* Merge sympa.conf(5) and list_config(5) into sympa_config(5).