Node-based editor
- https://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/state-machine-interface
- http://forum.unity3d.com/threads/simple-node-editor.189230/
- useful for AI and sequencing
- http://forum.unity3d.com/threads/flowcanvas-inspired-by-unreal-blueprints.245646/
- http://forum.unity3d.com/threads/nodecanvas-behaviour-trees-state-machines-dialogue-trees.227190/
- http://stackoverflow.com/questions/17593101/how-to-write-a-gui-editor-for-graph-or-tree-structures