[vreg] move base registry implementation to logilab.common. Closes #1916014 A new logilab.common.registry module has been created with content from * cw.vreg (the whole things that was in there) * cw.appobject (base selectors and all). In the process, we've done some renaming: * former selector functions are now known as "predicate", though you still use predicates to build an object'selector * hence `objectify_selector` decorator is now `objectify_predicate` * the top level registry is now `RegistryStore` (was `VRegistry`) Also there is no more need for the @lltrace decorator. On the CubicWeb side, the `selectors` module has been renamed to `predicates`. There should be full backward compat with proper deprecation warnings.

The personal information describing a User can be modified using the edit form
of the user. You can access it through the dropdown-menu under the link on the
top-right of the window, labeled by your login. In this menu, click the
"profile" link to go to this form.

Each user can as well customize the site appearance using the "user's
preferences" link in this menu. This will show you a form to configure which
boxes are displayed, in which order, etc...

.. image:: doc/images/userprefs