Release TensorFlow.NET v0.32, TensorFlow.Keras v0.3.

fix is_build_function in Layer.

release 0.20.

Supported for forced singlethreading

- Separated multithreading related methods to classname.threading.cs partial file
- ops: Added enforce_singlethreading(), enforce_multithreading()

v0.12 released

change text.

released v0.9.0.

add predict for logistic regression.

released 0.1.0 and updated doc.