[migration/3.14.4] use the right API else we break sqlserver instances (closes #2211248)

backport stable

[devtools] make a copy of the xvfb-run script so we can kill it properly Since changeset a3d3bdd46463 we don't run firefox directly but through a wrapper script. This meant that on stopping the test, we would kill that wrapper script but leave the Xvfb server and firefox processes running. So make a local copy of xvfb-run, and make it kill Xvfb when it goes down, not just when its client exits.

[ajax] use AJAX_BASE_URL instead of JSON_BASE_URL JSON_BASE_URL / 'json' should be replaced by AJAX_BASE_URL / 'ajax'

[web/config] refactor initialization of the data url Common logic have been moved in a dedicated `data_relpath` function.

backport stable

[test] create temporary directory with meaningfull prefix It will help cleanup temporary directory when cubicweb test failed to cleanup themself.

[schema] make cubicweb 3.14 compatible with yams 0.35

[test] fix ReST extensions tests

[web/controller] fix some cases where _cwmsgid may appears twice the Way the URL was build led to double _cwmsgid parameter in the URL query, which led in turn to a crash. We use _cw.rebuild_url to update new params instead of append_url_params which merely does a textual concatenation.

[reledit, autoform] move reledit_form definition in reledit.py No deprecation handling needed, reledit_form is new in CW 3.15

[hg] ignore ldap database

[ldap migration] use unicode strings

[ldapfeed] fix synchronisation crash: ldap attributes are given while we want cw attributes and name errors in method checking if a dn still exists in ldap