----------------------
* Added `Purge`` event and ``IPurgeable` and ``IPurgePaths`` interfaces.
Although this package doesn't provide any purging support, it is convenient
to keep the interfaces necessary for other packages to describe their cache
purging behaviour here. This allows a relatively harmless dependency on
z3c.caching, even in generic code, as distinct from a higher-level,
application server specific framework.
[optilude]
* Added concept of an explicitly declare ruleset type. Optional by default,
but can be made required by setting `explicit` to `True`.
[optilude]
* Added ``ILastModified`` implementation for a view which delegates to the
view's context.
[optilude]
* Added ``enumerateTypes()`` method to the registry, used to list all currently
used cache rule ids.
[optilude]
* Made the registry use the ZCA more directly.
[matthewwilkes]