Z3c.authenticator

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- Bugfix: the method specialGroups applied groups everytime the method get
called even if the group was already applied. This is a problem if the
global shared unauthenticated principal instance is used because it will
apply similar groups till the server get restarted and a new principal
instance is used.

- Feature: added getUserByLogin to IUserContainer

- Added a test for user migration (that they will keep their ID)

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- Update dependencies:

* Use ``zope.container`` instead of ``zope.app.container``.
* Use ``zope.site`` instead of ``zope.app.component``.
* Use ``zope.authentication`` and ``zope.principalregistry`` instead
of ``zope.app.security``.
* Use ``zope.password`` instead of maintaining a copy of password
managers.

- Drop dependency on z3c.i18n and recreate a message factory instead.

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- Bugfix: Failed miserably on challenge on pages having non-ASCII names.
(Backport from 0.7.2)

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- Backport bugfix 0.7.1 to 0.6.1. See branches/roger-0.6.0

the method specialGroups applied groups everytime the method get
called even if the group was already applied. This is a problem if the
global shared unauthenticated principal instance is used because it will
apply similar groups till the server get restarted and a new principal
instance is used.

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- Feature: added support for local IUnauthenticatedPrincipal. This is usefull
if you need to apply local roles to IUnauthenticatedPrincipal. This was not
possible before and is not possible in zope.app.authentication

- Feature: implemented initial grant view based on ISource widget. Note, this
source widget terms implementation which is very complex to understand will
get moved to z3c.from if we fixed the ITerm dependency. Which means ITerm
needs to get moved out of zope.app.form first.

- Feature: added support for next utility lookup in authenticate call. By
default the principals from the global principalregistry get involved now.
You can disable this feature by setting includeNextUtilityForAuthenticate to
False.

- Feature: added PrincipalRegistryAuthenticatorPlugin which allows to
authenticate principals defined in global principal registry.

- Feature: implemented z3c.form prefix support in SessionCredentialsPlugin. Now
there is an option called prefixes which can be used for define a list of
used z3c.form prefixes. This makes it simpler for supporting different forms
and adjust the credential extraction.

- Renamed IGroupPrincipal to IFoundGroup which makes it more understandable
why this adapter implementation is needed. The IFoundGroup adapter is now
also used for zope.security.interfaces.IGroup principals. This makes it
possible to use them in the new principalregistry credential. Provide
deprecation message for the old IGroupPrincipal implementation.

- Removed dependency for zapi. But it's not really gone since other packages
use zapi too.

- Removed unused InvalidPrincipalIds and InvalidGroupId exceptions

- Removed unused IMemberAwareGroup support. This interface is not used in zope
at all.

- Added documentation for Pypi home page.

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- Cleanup imports and adjust dependencies