[server] Refactor Repository.register_user into a CubicWeb service (closes #3020639) [jcr: move commit to the caller; add item in release notes; fix NameErrors]

[migration] set a cnxset before process_script() Not pretty, but I don't have a better idea right now and this at least ensures migration scripts get run in the expected environment and can access sql stuff as before.

[server] make internal_cnx get and keep a connection to the db - internal_session worked that way - it's less surprising for users if their internal connections "just work", rather than having to deal with the cnxset when using low-level APIs Includes a backout of 3f62606c01a2 "[repo] Fix register_user" which is no longer needed. Depend on logilab-database 1.12.1 to avoid errors due to pointless check in python's sqlite3 binding.

[server/session] make commit/rollback obey ensure_cnx_set Inside the ensure_cnx_set context manager, commit and rollback aren't allowed to dispose of the cnxset.

[repo] fix deprecation messages for stats and gc_stats

[cwconfig] use "foo not in bar" instead of "not foo in bar"

[debian] Add Breaks on a few cubes that need changes for 3.19 - mercurial_server is affected by composite deletion changes - forgotpwd relied on session data to be forwarded to notification view - registration hooks into the authentication stack

[hooks] run cascading delete hook later Applications may have their own before_delete_entity hooks that rely on the composite relations still existing.

[devtools] set PGPORT/PGHOST when calling pg_ctl start Helps pg_ctl find the socket on squeeze, otherwise it looks in /var/run/postgresql.

[server/test] update to deal with lgdb sqlserver fix See https://www.logilab.org/ticket/235748