[hooks/syncschema] work with connections not sessions
What's new in CubicWeb 3.18?============================The migration script does not handle sqlite nor mysql instances.New functionalities--------------------* add a security debugging tool (see `#2920304 <http://www.cubicweb.org/2920304>`_)* introduce an `add` permission on attributes, to be interpreted at entity creation time only and allow the implementation of complex`update` rules that don't block entity creation (before that the`update` attribute permission was interpreted at entity creation and update time)* the primary view display controller (uicfg) now has a`set_fields_order` method similar to the one available for forms* new method `ResultSet.one(col=0)` to retrive a single entity and enforce the result has only one row (see `#3352314 https://www.cubicweb.org/ticket/3352314`_)* new method `RequestSessionBase.find` to look for entities (see `#3361290 https://www.cubicweb.org/ticket/3361290`_)* the embedded jQuery copy has been updated to version 1.10.2, and jQuery UI to version 1.10.3.* initial support for wsgi for the debug mode, available through the new``wsgi`` cubicweb-ctl command, which can use either python's builtin wsgi server or the werkzeug module if present.* a ``rql-table`` directive is now available in ReST fields* cubicweb-ctl upgrade can now generate the static data resource directory directly, without a manual call to gen-static-datadir.API changes-----------* not really an API change, but the entity permission checks are now systematically deferred to an operation, instead of a) trying in a hook and b) if it failed, retrying later in an operation* The default value storage for attributes is no longer String, but Bytes. This opens the road to storing arbitrary python objects, e.g. numpy arrays, and fixes a bug where default values whose truth value was False were not properly migrated.*`symmetric` relations are no more handled by an rql rewrite but are now handled with hooks (from the `activeintegrity` category); this may have some consequences for applications that do low-level database manipulations or at times disable (some) hooks.*`unique together` constraints (multi-columns unicity constraints) get a `name` attribute that maps the CubicWeb contraint entities to corresponding backend index.* BreadCrumbEntityVComponent's open_breadcrumbs method now includes the first breadcrumbs separator* entities can be compared for equality and hashed* the ``on_fire_transition`` predicate accepts a sequence of possible transition names* the GROUP_CONCAT rql aggregate function no longer repeats duplicate values, on the sqlite and postgresql backendsDeprecation---------------------*``pyrorql`` sources have been deprecated. Multisource will be fully dropped in the next version. If you are still using pyrorql, switch to ``datafeed``**NOW**!* the old multi-source system*`find_one_entity` and `find_entities` in favor of `find` (see `#3361290 https://www.cubicweb.org/ticket/3361290`_)* the `TmpFileViewMixin` and `TmpPngView` classes (see `#3400448 https://www.cubicweb.org/ticket/3400448`_)Deprecated Code Drops----------------------*``ldapuser`` have been dropped; use ``ldapfeed`` now (see `#2936496 <http://www.cubicweb.org/2936496>`_)* action ``GotRhythm`` was removed, make sure you do not import it in your cubes (even to unregister it) (see `#3093362 <http://www.cubicweb.org/3093362>`_)* all 3.8 backward compat is gone* all 3.9 backward compat (including the javascript side) is gone* the ``twisted`` (web-only) instance type has been removed