cleanup
use IVindowBackend in Swf
IWrappedGraph<TItem, TEdge> introduced | GraphExtensions.Unwrap<TItem, TEdge> | use Unwrap
GraphPairExtension TODO: use IWrappedGraph
ThingGraphMaintenance introduced | ThingGraphMaintenance.RefreshCompression used in TestCaseFactory as CurrentProblem
SwfTestCaseFactory based on TestCaseFactoryBase introduced | TestCaseFactory008 made obsolte
SampleGraphSceneFactory.EnsureShapes introduced |  SampleGraphSceneFactory.Populate brings Nodes and Edges into view | TODO: maybe EnsureShapes  is obsolte, prove that
ContentViewManager.Dispose and HtmlContentViewer enhanced to ensure that WebBrowser disposes
removed obsolte tests