AdaNet v0.6.0

• Officially support AdaNet on TPU using adanet.TPUEstimator with adanet.Estimator feature parity.
• Support dictionary candidate pools in adanet.AutoEnsembleEstimator constructor to specify human-readable candidate names.
• Improve AutoEnsembleEstimator ability to handling custom tf.estimator.Estimator subclasses.
• Introduce adanet.ensemble which contains interfaces and examples of ways to learn ensembles using AdaNet. Users can now extend AdaNet to use custom ensemble-learning methods.
• Record TensorBoard scalar, image, histogram, and audio summaries on TPU during training.
• Add debug mode to help detect NaNs and Infs during training.
• Improve subnetwork tf.train.SessionRunHook support to handle more edge cases.
• Maintain compatibility with TensorFlow versions 1.9 thru 1.13 Only works for TensorFlow version >=1.13. Fixed in AdaNet v0.6.1.
• Improve documentation including adding 'Getting Started' documentation to adanet.readthedocs.io.
• BREAKING CHANGE: Importing the adanet.subnetwork package using from adanet.core import subnetwork will no longer work, because the package was moved to the adanet/subnetwork directory. Most users should already be using adanet.subnetwork or from adanet import subnetwork, and should not be affected.