Plone.app.viewletmanager

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- Specified package dependencies.
[hannosch]

- Made the manager code more tolerant and not fail when no storage is found.
[hannosch]

- Made the manage-viewlets screen use the 'managedPortlet' CSS class instead
of 'portlet', so it's more usable with a custom theme. This closes
http://dev.plone.org/plone/ticket/8391.
[davisagli]

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- Fixed bogus AttributeError masking the real ExpatError on syntax errors in
viewlets.xml. (See test in r21161.)
[davisagli]

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- Separated the base functionality and the parts necessary for TTW
customization into two classes, so we can use this manager in the html
head.
[fschulze]

- Fix a syntax error in the export/import code
[wichert]

- Add a HISTORY.txt file
[wichert]

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- Initial release