Zope-component

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- Fix a bug introduced by recent refactoring, where passing
``CheckerPublic`` to ``securityAdapterFactory`` wrongly wrapped the factory
into a ``LocatingUntrustedAdapterFactory``.

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- Modify the tests to avoid allowing the tested testrunner to be influenced
by options of the outer testrunner, such a the ``-v`` option.

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- Add testlayer support. It is now possible to load a ZCML file within
tests more easily. See ``src/zope/component/testlayer.py`` and
``src/zope/component/testlayer.txt``.

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- Remove the dependencies on ``zope.proxy`` and ``zope.security`` from the
zcml extra: ``zope.component`` no longer has a hard dependency on them;
the support for security proxied components ZCML registrations is enabled
only if ``zope.security`` and ``zope.proxy`` are available.

- Move the ``IPossibleSite`` and ``ISite`` interfaces here from
``zope.location`` as they are dealing with ``zope.component``'s concept of
a site, but not with location.

- Move the ``zope.site.hooks`` functionality to ``zope.component.hooks`` as it
isn't actually dealing with ``zope.site``'s concept of a site.

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- Fix a problem, where ``queryNextUtility`` could fail if the context could
not be adapted to a ``IComponentLookup``.

- Fix 2 related bugs:

When a utility is registered and there was previously a utility
registered for the same interface and name, then the old utility is
unregistered. The 2 bugs related to this:

- There was no ``Unregistered`` for the implicit unregistration. Now
there is.

- The old utility was still held and returned by
``getAllUtilitiesRegisteredFor``. In other words, it was still
considered registered, eeven though it wasn't. A particularly
negative consequence of this is that the utility is held in memory
or in the database even though it isn't used.

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- Ensure that ``HookableTests`` are run by the testrunner.

- Add ``zope:view`` and ``zope:resource`` implementations into
``zope.component.zcml`` (dependency loaded with ``zope.component [zcml]``).