… state to playingBackAuto Closes #26

(cherry picked from commit 06c510e)

(cherry picked from commit a862604887a9b18878db9ce043e63bdb8b359343)

Instead of a list of weights, it is now a dictionary of weights, with the vertex number as key. This can reduce the file size to 3% of the size.

1. Don't prune unless it is a polygon mesh. It is possible to prune on nurbs, but it needs more bug-testing. For example, on nurbs, you can't just specify the transform node. It will fail.

2. Don't use polyEvaluate on nurbsSurfaces or nurbsCurves. Count the CVs instead. By making this change, you can now export and import skinning on nurbs or polygons.

3. It now counts all the CVs or vtxs on multiple shape nodes. But the file format does NOT support multiple shape nodes yet! Each individual shape node under a transform would get a separate skinCluster.

Test for basestring instead of str. Skin weights are working fine because it uses dict.get(str(vtx))

I was checking the type of the key for binary vs. json. There is no need. Just cast the key as an int.