be removed soon.
*   `dot.h` / DotGraph was removed (it was an early analysis tool prior to
    TensorBoard, no longer that useful). It remains in history should someone
    find the code useful.
*   re2 / regexp.h was removed from being a public interface of TF. Should users
    need regular expressions, they should depend on the RE2 library directly
    rather than via TensorFlow.

## Thanks to our Contributors