* CORE_config: New.
* HTTP_services: Declare an "autotesting" HTTP service.
* HTML_autotest: New (web interfaces for the autotest subsystem).
* I18N: More UI strings.
* CORE_config: Define a "current_language" parameter.
* I18N: Use it.
CORE_autotest: New (infrastructure and driver for autotesting subsystem).
A basic reactive communication layer between the client and the server.

* CORE_client_reaction, HTML_reactive: New.
* HTML_autotest.eliom: Use it, stupidly for the moment.