Plone.app.layout

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- Fix issue when dealing with empty version histories in history viewlet.
[alecm]

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- Make ContentHistoryViewlet use new metadata only history method to
speed up listing.
[alecm]

- Make ContentHistoryViewlet check if context isVersionable.
[elro]

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- Changed the search and author header links to respect the navigation root.
[hannosch]

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- Filter not-interesting history entries in content history viewlet. This
prevents an empty history viewlet from being shown.
[wichert]

- Add a new content history viewlet which combines the full workflow history
and content versions. Render this instead of the workflow history viewlet.
[wichert]

- Fixed querystring in CSS validation link in viewlets/colophon.pt
There was an ampersand where the leading "?" should have been.
http://dev.plone.org/plone/ticket/9054
[siebo]

- Fixed "region-content" id twice in dashboard.pt, replaced one by "content".
Fixes http://dev.plone.org/plone/ticket/8932
[vincentfretin]

- Author link tag should follow same rules as byline viewlet.
[elro]

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- Fixed i18n in content_history template.
There were two nested msgids and dynamic content.
[vincentfretin]

- Removed stray span tags in the comment byline.
[limi]

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- Added navigation_root_url to the common viewlets base class. Adjusted the
various viewlets templates to use the new attribute. Changed the dashboard
view to be available on an INavigationRoot.
This implements http://plone.org/products/plone/roadmap/234
[calvinhp]

- Default to using the content history viewlet instead of the workflow history
viewlet.
[wichert]

- Add options to show differences between consecutive versions, and revert to
and preview older revisions to the content history viewlet.
[wichert]

- Use the new history view from CMFEditions instead of the crufty old form.
[wichert]