Added XmlExport with UnitTest
Adapted XmlExport to work with IEntity instead of Eav.Entity
Extened XmlExport with correc Value Serialization
Simplified XmlExport class
Added XmlImport (incomplete)
Extended EavContext (Persistence) to log Entity-Changes to DataTimeline using XmlExport
Extended EavContext with Methods to get and restore Entity Version(s)
Added ItemHistory Control
Added Item Version Details Control
Extended ItemVersionDetails with Details of specific Version.
Minor Refactoring EavManagement-Control.
Merge branch 'master' to include changes of 2bg