Fix #295 — Add domain blacklist feature

Primary `auth.conf` etc. won't be used by non-primary domains

`make distcheck` fails

[bug] Primary `auth.conf`, `crawlers_detection.conf` and `trusted_applications.conf` won't be used by non-primary domains by default.

Add a global quiet_subscription setting which enforce the "quiet add" policy

WWSympa: Deprecate sympa_altemails cookie #487

File extension may contain spaces by using gettext_strftime()

Long email addresses in system messages may be folded #502

WWSympa: Loading home page takes long time

WWSympa: Older CSS files would be cleared

Allow to use Gitlab CI

Avoid two-args open and bareword filehandle. Ignore errors.

Fix #301 — Add global mail signature feature

Fixed by preventing folding words matching email regexp.

When user is logged-in, Sympa collects information about membership/adminship among all lists, content of moderation spool and so on, though they will never be used.  Fixed by removing code collectiong information in vain. Deprecated web_tt2/news.tt2.

For those who prefer to work on Gitlab (or use Gitlab CI while using
Github[1]), here's a working .gitlab-ci.yml.

Docker images for the CI are published on
https://framagit.org/luc/DockerFiles/tree/master/sympa-perl

[1] See https://about.gitlab.com/solutions/github/

Fixed by clearing older style.css* and lang.css* under $CSSDIR when they would be updated.

Note: Among files under $CSSDIR, fullPage.css*, print.css* and print-preview.css* will no longer be used nor updated. These may be removed manuallly.

[change] ldap_authentication() does no longer perform search operations twice, because attributes of user's entry has been retrieved by the first operation.

[change] Deprecate sympa_altemails cookie.  Also, obsolete alternative_email_attribute parameter in ldap paragraph of auth.conf.