v2.1.0

New features:

• Datasets expose info.dataset_size and info.download_size. All datasets generated with 2.1.0 cannot be loaded with previous version (previous datasets can be read with 2.1.0 however).
• Auto-caching small datasets. in_memory argument is deprecated and will be removed in a future version.
• Datasets expose their cardinality num_examples = tf.data.experimental.cardinality(ds) (Requires tf-nightly or TF >= 2.2.0)
• Get the number of example in a sub-splits with: info.splits['train[70%:]'].num_examples