document-tree bugfix: unpublish wasn't possible

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@3855 1f8fe7d8-47f0-464c-8d0a-336f4953ab05
handle invalid admin sessions

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@3856 1f8fe7d8-47f0-464c-8d0a-336f4953ab05
properties: deferred (lazy) loading of elements (objects, assets, documents)

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@3857 1f8fe7d8-47f0-464c-8d0a-336f4953ab05
added modificationdate to version preview

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@3858 1f8fe7d8-47f0-464c-8d0a-336f4953ab05
build auto version (2950) ...

git-svn-id: http://www.pimcore.org/svn/pimcore/private/core/trunk@3859 1f8fe7d8-47f0-464c-8d0a-336f4953ab05