[doc/3.16] complete description of what changed

[rql sources] uses an URL as remote host address for pyro/zmq rql sources, instead of extra configuration parameters. Follows modification of dbapi.connect api. Closes #2539822

[repo sources] move handling of source's url into abstract source as this becomes shared by most sources prepare #2539822

[db-api] rename repo_connect into _repo_connect to mark it private. Closes #2521848

[repository sources] copy source configuration: source's __init__ modify it while config.sources() return a cached dictionary which shouldn't be modified This causes pb since f8aa87a773b2 (though it's unclear why it hasn't been a problem before). Closes #2521848

cleanup repository connect doc: cnxtype is now deprecated / base_url has never been given that way. Follow #2521848

prefix "tcp://" zmq uris with "zmqpickle" (closes #2574114) * it turns "tcp://" into "zmqpickle-tcp://" * will leave room for future non-pickling communications using zmq

[db-api/configuration] simplify db-api and configuration so that all the connection information is in the repository url, closes #2521848 eg no more specific option of pyro ns host, group, etc. This also fixes broken ZMQ sources. Changes: * dropped pyro-ns-host, pyro-instance-id, pyro-ns-group from client side config, in favor of repository-uri. No migration done, supposing there is **no web-only config** in the wild. Also stop discovering the connection method through the repo_method class attribute of the configuration, varying according to the configuration class. This is a first step on the way to a simpler configuration handling. Notice those pyro options are still available for repository only / all-in-one configurations as they are needed to configure the pyro server. * stop telling connection method using ConnectionProperties, this is so boring. Also, drop _cnxtype from Connection and cnxtype from Session. The former is replaced by a is_repo_in_memory property and the later is totaly useless. * deprecate in_memory_cnx which becomes useless, use _repo_connect instead

[ldap test] ensure slapdd launch went fine and move ldapfeed setUp to parent class, as all ldap sources deal with url

[web/uihelper,uicfg] transform uihelper functions into uicfg objects methods (closes #2543949)