Add numbin as another serialization library

Hi, I'm the author of [numbin](https://github.com/mosecorg/numbin) (An efficient binary serialization format for numpy data.) I just found this repo and I wonder if you will accept numbin as another serialization library.

Check the benchmark [here](https://github.com/mosecorg/numbin#benchmark).

BTW, I don't know there is a library called msgpack-numpy before I develop numbin. After explore the source code, I think numbin would provide better performance and flexibility.