- Added a ClearAllChains method to PolylineSceneLayer --> revision must change when calling it ==> BumpRevision has been added to base class - Added some docs = Added GetMinDepth + GetMaxDepth to Scene2D (to alleviate the need for app- specific "Z depth registry" : clients may simply add a new layer on top or at the bottom of the existing layer set. - Added the line tracker measurement tools, commands and trackers. Generic base classes + Line measure - started work on the line measure handles