hotline#150820 : Newsletters : updating newsletter subscription information display when user subscribes or unsubscribes

You can now build dynamic facets/thesaurus on a list of of domains.
- activation by admin var ENABLE_FACETS_ON_DOMAINS
- configuration screen in Bokeh admin > domains > facets
- adds Cosmogramme phase to index records according to the dynamic
facets
- restore thesaurus CODE field usage as a grouping field : UNIMARC for dynamic facets on unimarc,
DOMAIN for those on domain
- minimum MariaDB version is now 10.3
- admin domains list now display user favorite indicator and OAI Spec
with link to ListRecords

+ fix coches suggestion communication between element and view helper

+ inspector_gadget able to display calls to community server

* do not fetch urls from cache server if no thumbnail in unimarc and
url_vignette already at NO
* do not save Class_Notice if thumbnails urls have not changed