This commit include lots of changes for pose editor.
Before, we use buttons to represent the transform controller for bones;
Now, we use nodes and edges to represent the bones, just like the nodes and edges for representing the guide spheres for mesh generating. There are advantages by doing this. Firstly, The edit UI for both mesh and pose are unified, secondly, it is possible to set a reference sheet for pose editing now, this is very important.
This new pose editor is inspired by the Eadweard Muybridge's work.
Jeremy Hu