Updated for OS X 10.10 SDK, converted to ARC, updated to adopt current best practices for Objective-C (including use of properties, autosynthesis, and literals), fixed warnings and can’t convert to ARC (errors), converted to modern Obj-C, upgraded nib file.

General updates.

Updated for Mac OS X 10.7, corrected "Container" and "Leaf" labels for items in UI.

Small application that illustrates how to implement drag and drop in an outline view.