See discussion: #1186

* 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

i.e. users not decided to delete, update nor keep.

even if one or more of data sources failed inclusion.

family_signoff action no longer does use one-time ticket.

Introduced Sympa::Tools::Text::slurp() to slurp text file applying Unicode sanitization and normalization. Note: Though Unicode::Normalize and Unicode::UTF8 are optional now, they would be mandatory in the future.

— Add prohibited_listnames setting (comma-separated list, with ability
to use a wildcard)
— Add prohibited_listnames_regex setting

The settings are cumulative. You can use one or the other or both.

May fix #672

A note:
Now create_list, create_automatic_list & update_automatic_list Request handlers won't take "listname" as an top-level parameter, but it must be included in an item of "parameters" parameter.

Thx @ikedas for advices

This will fix several bugs due to confusion with function and parameter.

A name of the source by which user was actually included will be stored in inclusion_label_* field of the table.

[-change] Database schema: inclusion_ext_* fields in subscriber_table and admin_table to give the last time of inclusion from external data sources.
"External" means that it is not include_sympa_list or not including list on local domain.
Note that if inclusion_ext_* field is updated, inclusion_* field must be updated at the same time.

Known bug:
  - If data source is a list included from the other external data source(s), it will be treated as non-external and move_user request on corresponding users will be allowed.

[change] Data sources: outdated users will be expired only when all data sources of the list has succeeded inclusion.
By this change, if there are data sources with nosync_time_ranges set, deletion of outdated users can be delayed 24 hours at most.
[change] Database schema: included_* and include_sources_* in subscriber_table and admin_table were deprecated.  inclusion_* fields will be used instead.

[feature] Now data sources won't overwrite existing gecos: It is assigned only when a new user is added (included) from data source, or when it is added (subscribed) by users.

Refactoring (mostly rewritten). Introducing new classes Sympa::Request::Handler::include, Sympa::DataSource and its subclasses. Sympa::Datasource was deprecated.

And some fixes:
  * [bug] Now include_remote_file, include_sympa_list and include_remote_sympa_list paragraphs may have nosync_time_ranges subparameter.  No reason they don't have it.  include_file stil doesn't have it.
  * [-feature] include_voot_group has not been implemented, and it was invalidated.
  * [bug] include_ldap_query and include_ldap_ca data sources did not implement "regex" option of "selection" subparameter.  Now they support it.
  * [bug] LDAP multiple values in custom attribute with include_ldap_ca was broken.
  * [-feature] include_sql_query and include_sql_ca stores inclusion data in temporary file so that big data sources will be handled safely.

Tentative change:
  * include_ldap_query, include_ldap_2level and include_sql_query won't clear (overwrite) gecos if retrieved value was empty or undefined.  Now they clear (overwrite) gecos in such cases.