[ajax] refactor/cleanup low-level ajax functions * loadxhtml/replacePageChunck/reload_component/reload_box deprecated in favor of loadXHTML / ajaxFuncArgs * some other cleanups in cubicweb.ajax.js * add js_render which will replace js_component (more generic, nicer argument passing handling)

[querier] test and fix potential bug in insertion query with multiple relations inside, caused by a name conflict. Also fix another bug non reproduced by using a set instead of a list (list may leads to compare entity instances which isn't allowed).

[form] avoid spurious warning subsequent for form's action refactoring w/ autoforms

backport stable

[web test] Add a CubicWebServerTC class to run test with a cw web serveur available.

[web server] vregistry may now be passed as named argument in CubicWebRootResource constructor This will be needed to start an http server for testing purpose. Also, server run command has now a debug name argument to set debug mode explicitly

[etwist] twisted won't install signal handler outside the main thread. This patch avoid some warning about this issue.

[vreg] ensure you can register an object from module not known yet. This ease registration of arbitrary objects during testing.

[web] cleanup use of config in web application initialisation

fix unit tests by not using the new create_eid implementation with sqlite Actually, fix a couple of issues with a previous attempt: * do not use double underscores as method patching will fail with these * old method must always be used with sqlite regardless of the no_sqlite_wrap attribute