Manual sidebar organizing

[vocksel]

Allow users to drag-and-drop items in the sidebar to reorganize it to their liking.

DataModel considerations

If moving an item also changes the Parent, how can we best support sync workflows? Tools like Rojo do not have bidirectional sync, so changes to the DataModel will not change the filesystem. Studio workflows should be able to handle this case just fine, but I don't suspect we have many Studio-only users as Flipbook is not well supported for that

If moving an item does not change the Parent, should the hierarchy persist between sessions?

• If yes, unless we have a global configuration (Flipbook configuration file #309) then two users of Flipbook will gradually become out of sync with each other. We also don't have a great way to robustly map files to instances between sessions. Right now we rely on GetFullName, and if a story is moved then the user's organizational link is broken.
• If no, it would be fairly trivial to allow users to organize their stories, but the inability to keep track of their changes might do more harm than good. A user taking time to organize their stories, only to find out later those changes didn't save would be frustrating