Plone.browserlayer

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- Add support for calling many times remove in export (ie:even when no corresponding layer is registered, remove option should not throw exception).
[toutpt]

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- Added uninstall support to browserlayer.xml with the 'remove' option.
[maurits]

- GS export xml is now repeatable. Before two consecutive exports could
yield differently ordered results.
[do3cc]

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- Update import of BeforeTraverseEvent to come from zope.traversing instead
of zope.app.publication.
[davisagli]

- Add MANIFEST.in
[WouterVH]

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- Make sure the layers don't get applied twice if the site is traversed more
than once (such as in a vhosting URL).
[davisagli]

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- Update license to GPL version 2 only.
[hannosch]

- Package metadata cleanup, require Zope2 distribution.
[hannosch]

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- Be more robust against broken layer registrations. These can occur when
packages with registered layers are removed.
[wichert]

- Clarified license and copyright.
[hannosch]

- Register ourselves for the more generic ISiteRoot from CMFCore and not
IPloneSiteRoot.
[hannosch]

- Declare test dependencies in an extra.
[hannosch]

- Specify package dependencies.
[hannosch]