GraphVisualEntityMapping: error in chaining
cleanup
ThingGraphExtensions.MergeThings: marker can be null
Merge branch 'master' of https://github.com/limada/limada
Db4oThingGraphSpot:  magic added
ConceptUsecase: ask before merge
SheetManager: catch exception if sheet loading goes wrong
SplitView0: invalidate display after search; otherwise it could happen that the search result is smaller than the old view, and some dirt remains