[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.
About this site
===============
This web application is based on the CubicWeb knowledge management system
from Logilab_. CubicWeb is made of an object database and a web
framework. It allows to develop an application by defining a set of
entities and their relationships, plus a set of views that present the
data selected from the object database using a specific query language.
This application has a precise schema_ and can be considered an
example of a semantic web database, as it can export the data to XML
and others formats and is not limited to publishing HTML.
Supported formats: |microformats|_ - JSON_ - |rss|_ - |dublincore|_
.. |microformats| image:: /data/microformats-button.png
.. _microformats: http://microformats.org
.. _JSON: http://www.json.org/
.. |rss| image:: /data/rss-button.png
.. _rss: http://www.rssboard.org
.. |dublincore| image:: /data/dublincore-button.png
.. _dublincore: http://dublincore.org
.. _Logilab: http://www.logilab.fr/
.. _schema: schema