[web] Exposes the undo feature to user through a undo-history view (closes #893940)
Whats new in CubicWeb 3.15
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API changes
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* The base registry implementation has been moved to a new
`logilab.common.registry` module (see #1916014). This includes code from :
* `cubicweb.vreg` (the whole things that was in there)
* `cw.appobject` (base selectors and all).
In the process, some renaming was done:
* the top level registry is now `RegistryStore` (was `VRegistry`), but that
should not impact cubicweb client code ;
* former selectors functions are now known as "predicate", though you still use
predicates to build an object'selector ;
* for consistency, the `objectify_selector` decoraror has hence be renamed to
`objectify_predicate` ;
* on the CubicWeb side, the `selectors` module has been renamed to
`predicates`.
Debugging refactoring dropped the more need for the `lltrace` decorator.
There should be full backward compat with proper deprecation warnings.
Notice the `yes` predicate and `objectify_predicate` decorator, as well as the
`traced_selection` function should now be imported from the
`logilab.common.registry` module.
Unintrusive API changes
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* new 'ldapfeed' source type, designed to replace 'ldapuser' source with
data-feed (i.e. copy based) source ideas.
RQL
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User interface changes
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Configuration
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Base schema changes
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Email address 'read' permission is now more restrictive: only managers and
users to which an address belong may see them. Application that wish other
settings should set them explicitly.